83 research outputs found
Online Knowledge Distillation via Mutual Contrastive Learning for Visual Recognition
The teacher-free online Knowledge Distillation (KD) aims to train an ensemble
of multiple student models collaboratively and distill knowledge from each
other. Although existing online KD methods achieve desirable performance, they
often focus on class probabilities as the core knowledge type, ignoring the
valuable feature representational information. We present a Mutual Contrastive
Learning (MCL) framework for online KD. The core idea of MCL is to perform
mutual interaction and transfer of contrastive distributions among a cohort of
networks in an online manner. Our MCL can aggregate cross-network embedding
information and maximize the lower bound to the mutual information between two
networks. This enables each network to learn extra contrastive knowledge from
others, leading to better feature representations, thus improving the
performance of visual recognition tasks. Beyond the final layer, we extend MCL
to intermediate layers and perform an adaptive layer-matching mechanism trained
by meta-optimization. Experiments on image classification and transfer learning
to visual recognition tasks show that layer-wise MCL can lead to consistent
performance gains against state-of-the-art online KD approaches. The
superiority demonstrates that layer-wise MCL can guide the network to generate
better feature representations. Our code is publicly avaliable at
https://github.com/winycg/L-MCL.Comment: 18 pages, accepted by IEEE Transactions on Pattern Analysis and
Machine Intelligence (TPAMI-2023
Lung Nodule Segmentation and Uncertain Region Prediction with an Uncertainty-Aware Attention Mechanism
Radiologists possess diverse training and clinical experiences, leading to
variations in the segmentation annotations of lung nodules and resulting in
segmentation uncertainty.Conventional methods typically select a single
annotation as the learning target or attempt to learn a latent space comprising
multiple annotations. However, these approaches fail to leverage the valuable
information inherent in the consensus and disagreements among the multiple
annotations. In this paper, we propose an Uncertainty-Aware Attention Mechanism
(UAAM) that utilizes consensus and disagreements among multiple annotations to
facilitate better segmentation. To this end, we introduce the Multi-Confidence
Mask (MCM), which combines a Low-Confidence (LC) Mask and a High-Confidence
(HC) Mask.The LC mask indicates regions with low segmentation confidence, where
radiologists may have different segmentation choices. Following UAAM, we
further design an Uncertainty-Guide Multi-Confidence Segmentation Network
(UGMCS-Net), which contains three modules: a Feature Extracting Module that
captures a general feature of a lung nodule, an Uncertainty-Aware Module that
produces three features for the the annotations' union, intersection, and
annotation set, and an Intersection-Union Constraining Module that uses
distances between the three features to balance the predictions of final
segmentation and MCM. To comprehensively demonstrate the performance of our
method, we propose a Complex Nodule Validation on LIDC-IDRI, which tests
UGMCS-Net's segmentation performance on lung nodules that are difficult to
segment using common methods. Experimental results demonstrate that our method
can significantly improve the segmentation performance on nodules that are
difficult to segment using conventional methods.Comment: 10 pages, 10 figures. We have reported a preliminary version of this
work in MICCAI 202
Expression of phospho-ERK1/2 and PI3-K in benign and malignant gallbladder lesions and its clinical and pathological correlations
Abstract Background An increasing number of studies have shown that ERK and PI3-K/AKT signaling pathways are involved in various human cancers including hepatocellular carcinoma and cholangiocarcinoma. However, few studies have examined gallbladder cancer specimens, and little is known about the clinical and pathological significance of ERK1/2 and PI3-K/AKT signaling changes in gallbladder adenocarcinoma. In this study, we examined phospho-ERK1/2 (p-ERK1/2) and PI3K expression and analyzed its clinicopathological impact in gallbladder adenocarcinoma. Methods Immunohistochemistry was used to detect and compare the frequency of p-ERK1/2 and PI3-K expression in gallbladder adenocarcinoma, peri-tumor tissues, adenomatous polyps, and chronic cholecystitis specimens. Results The positive staining for p-EKR1/2 and PI3-K were 63/108 (58.3%) and 55/108 (50.9%) in gallbladder adenocarcinoma; 14/46 (30.4%) and 5/46 (10.1%) in peri-tumor tissues; 3/15 (20%) and 3/15 (20%) in adenomatous polyps; and 4/35 (11.4%) and 3/35 (8.6%) in chronic cholecystitis. The positive rate of p-ERK1/2 or PI3-K in gallbladder adenocarcinoma was significantly higher than that in peri-tumor tissue (both, P P P P P P P P = 0.062) was associated with decreased overall survival. Multivariate Cox regression analysis showed that increased p-ERK1/2 expression was an independent prognostic predictor in gallbladder carcinoma (P = 0.028). Conclusion Increased expression of p-ERK1/2 and PI3K might contribute to gallbladder carcinogenesis. p-ERK1/2 over-expression is correlated with decreased survival and therefore may serve as an important biological marker in development of gallbladder adenocarcinoma.</p
Bacterial Lifestyle in a Deep-sea Hydrothermal Vent Chimney Revealed by the Genome Sequence of the Thermophilic Bacterium Deferribacter desulfuricans SSM1
The complete genome sequence of the thermophilic sulphur-reducing bacterium, Deferribacter desulfuricans SMM1, isolated from a hydrothermal vent chimney has been determined. The genome comprises a single circular chromosome of 2 234 389 bp and a megaplasmid of 308 544 bp. Many genes encoded in the genome are most similar to the genes of sulphur- or sulphate-reducing bacterial species within Deltaproteobacteria. The reconstructed central metabolisms showed a heterotrophic lifestyle primarily driven by C1 to C3 organics, e.g. formate, acetate, and pyruvate, and also suggested that the inability of autotrophy via a reductive tricarboxylic acid cycle may be due to the lack of ATP-dependent citrate lyase. In addition, the genome encodes numerous genes for chemoreceptors, chemotaxis-like systems, and signal transduction machineries. These signalling networks may be linked to this bacterium's versatile energy metabolisms and may provide ecophysiological advantages for D. desulfuricans SSM1 thriving in the physically and chemically fluctuating environments near hydrothermal vents. This is the first genome sequence from the phylum Deferribacteres
Evolutionary history of the OmpR/IIIA family of signal transduction two component systems in Lactobacillaceae and Leuconostocaceae
<p>Abstract</p> <p>Background</p> <p>Two component systems (TCS) are signal transduction pathways which typically consist of a sensor histidine kinase (HK) and a response regulator (RR). In this study, we have analyzed the evolution of TCS of the OmpR/IIIA family in <it>Lactobacillaceae </it>and <it>Leuconostocaceae</it>, two families belonging to the group of lactic acid bacteria (LAB). LAB colonize nutrient-rich environments such as foodstuffs, plant materials and the gastrointestinal tract of animals thus driving the study of this group of both basic and applied interest.</p> <p>Results</p> <p>The genomes of 19 strains belonging to 16 different species have been analyzed. The number of TCS encoded by the strains considered in this study varied between 4 in <it>Lactobacillus helveticus </it>and 17 in <it>Lactobacillus casei</it>. The OmpR/IIIA family was the most prevalent in <it>Lactobacillaceae </it>accounting for 71% of the TCS present in this group. The phylogenetic analysis shows that no new TCS of this family has recently evolved in these <it>Lactobacillaceae </it>by either lineage-specific gene expansion or domain shuffling. Furthermore, no clear evidence of non-orthologous replacements of either RR or HK partners has been obtained, thus indicating that coevolution of cognate RR and HKs has been prevalent in <it>Lactobacillaceae</it>.</p> <p>Conclusions</p> <p>The results obtained suggest that vertical inheritance of TCS present in the last common ancestor and lineage-specific gene losses appear as the main evolutionary forces involved in their evolution in <it>Lactobacillaceae</it>, although some HGT events cannot be ruled out. This would agree with the genomic analyses of <it>Lactobacillales </it>which show that gene losses have been a major trend in the evolution of this group.</p
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