109 research outputs found
Keypoint-Augmented Self-Supervised Learning for Medical Image Segmentation with Limited Annotation
Pretraining CNN models (i.e., UNet) through self-supervision has become a
powerful approach to facilitate medical image segmentation under low annotation
regimes. Recent contrastive learning methods encourage similar global
representations when the same image undergoes different transformations, or
enforce invariance across different image/patch features that are intrinsically
correlated. However, CNN-extracted global and local features are limited in
capturing long-range spatial dependencies that are essential in biological
anatomy. To this end, we present a keypoint-augmented fusion layer that
extracts representations preserving both short- and long-range self-attention.
In particular, we augment the CNN feature map at multiple scales by
incorporating an additional input that learns long-range spatial self-attention
among localized keypoint features. Further, we introduce both global and local
self-supervised pretraining for the framework. At the global scale, we obtain
global representations from both the bottleneck of the UNet, and by aggregating
multiscale keypoint features. These global features are subsequently
regularized through image-level contrastive objectives. At the local scale, we
define a distance-based criterion to first establish correspondences among
keypoints and encourage similarity between their features. Through extensive
experiments on both MRI and CT segmentation tasks, we demonstrate the
architectural advantages of our proposed method in comparison to both CNN and
Transformer-based UNets, when all architectures are trained with randomly
initialized weights. With our proposed pretraining strategy, our method further
outperforms existing SSL methods by producing more robust self-attention and
achieving state-of-the-art segmentation results. The code is available at
https://github.com/zshyang/kaf.git.Comment: Camera ready for NeurIPS 2023. Code available at
https://github.com/zshyang/kaf.gi
Excess DHA Induces Liver Injury via Lipid Peroxidation and Gut Microbiota-Derived Lipopolysaccharide in Zebrafish
Being highly unsaturated, n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) are
prone to lipid peroxidation. In this study, zebrafish were fed with low-fat diet (LFD), high-fat
diet (HFD), or 2% DHA-supplemented HFD (HFDHA2.0). To study the possible negative
effects of the high level of dietary DHA, growth rates, blood chemistry, liver histology,
hepatic oxidative stress, apoptosis, and inflammatory processes were assessed. The
cell studies were used to quantify the effects of DHA and antioxidant on cellular
lipid peroxidation and viability. The possible interaction between gut microbiota and
zebrafish host was evaluated in vitro. HFDHA2.0 had no effect on hepatic lipid level
but induced liver injury, oxidative stress, and hepatocellular apoptosis, including intrinsic
and death receptor-induced apoptosis. Besides, the inclusion of 2% DHA in HFD
increased the abundance of Proteobacteria in gut microbiota and serum endotoxin
level. In the zebrafish liver cell model, DHA activated intrinsic apoptosis while the
antioxidant 4-hydroxy-Tempo (tempo) inhibited the pro-apoptotic negative effects of
DHA. The apoptosis induced by lipopolysaccharide (LPS) was unaffected by the addition
of tempo. In conclusion, the excess DHA supplementation generates hepatocellular
apoptosis-related injury to the liver. The processes might propagate along at least two
routes, involving lipid peroxidation and gut microbiota-generated LPS
Intestinal Cetobacterium and acetate modify glucose homeostasis via parasympathetic activation in zebrafish.
peer reviewedThe capability of carbohydrate utilization in fish is limited compared to mammals. It has scientific and practical significance to improve the ability of fish to use carbohydrates. The efficiency of dietary carbohydrate utilization varies among fish with different feeding habits, which are associated with differential intestinal microbiota. In this study, we found that zebrafish fed with omnivorous diet (OD) and herbivorous diet (HD) showed better glucose homeostasis compared with carnivorous diet (CD) fed counterpart and the differential glucose utilization efficiency was attributable to the intestinal microbiota. The commensal bacterium Cetobacterium somerae, an acetate producer, was enriched in OD and HD groups, and administration of C. somerae in both adult zebrafish and gnotobiotic larval zebrafish models resulted in improved glucose homeostasis and increased insulin expression, supporting a causative role of C. somerae enrichment in glucose homeostasis in fish. The enrichment of C. somerae was constantly associated with higher acetate levels, and dietary supplementation of acetate promotes glucose utilization in zebrafish, suggesting a contribution of acetate in the function of C. somerae. Furthermore, we found that the beneficial effect of both acetate and C. somerae on glucose homeostasis was mediated through parasympathetic activation. Overall, this work highlights the existence of a C. somerae-brain axis in the regulation of glucose homeostasis in fish and suggests a role of acetate in mediating the axis function. Our results suggest potential strategies for improvement of fish carbohydrate utilization
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A Critical Review of Laser Shock Peening of Aircraft Engine Components
Article describes how many aviation accidents are caused by the failure of aircraft engine components, and engine blades are especially vulnerable to high-cycle fatigue fracture in severe working environments as well as to impact damage caused by foreign objects. This review provides an overview of the development of LSP for use in treating aircraft engine components over the past three decades, with a brief introduction to the development of high-energy pulsed lasers for LSP
Microwave assisted low temperature synthesis of MnZn ferrite nanoparticles
MnZnFe2O4ferrite nanoparticles were prepared by co-precipitation method using a microwave heating system at temperature of 100 °C. X-ray diffraction reveals the samples as prepared are pure ferrite nanocrystalline phase, transmission electron microscopy image analysis shows particles are in agglomeration state with an average size of about 10 nm, furthermore, crystal size of samples are increased with longer microwave heating
Autotoxins in continuous tobacco cropping soils and their management
Tobacco belongs to the family Solanaceae, which easily forms continuous cropping obstacles. Continuous cropping exacerbates the accumulation of autotoxins in tobacco rhizospheric soil, affects the normal metabolism and growth of plants, changes soil microecology, and severely reduces the yield and quality of tobacco. In this study, the types and composition of tobacco autotoxins under continuous cropping systems are summarized, and a model is proposed, suggesting that autotoxins can cause toxicity to tobacco plants at the cell level, plant-growth level, and physiological process level, negatively affecting soil microbial life activities, population number, and community structure and disrupting soil microecology. A combined strategy for managing tobacco autotoxicity is proposed based on the breeding of superior varieties, and this approach can be combined with adjustments to cropping systems, the induction of plant immunity, and the optimization of cultivation and biological control measures. Additionally, future research directions are suggested and challenges associated with autotoxicity are provided. This study aims to serve as a reference and provide inspirations needed to develop green and sustainable strategies and alleviate the continuous cropping obstacles of tobacco. It also acts as a reference for resolving continuous cropping challenges in other crops
Monoclonal Antibodies against Accumulation-Associated Protein Affect EPS Biosynthesis and Enhance Bacterial Accumulation of Staphylococcus epidermidis
Because there is no effective antibiotic to eradicate Staphylococcus epidermidis biofilm infections that lead to the failure of medical device implantations, the development of anti-biofilm vaccines is necessary. Biofilm formation by S. epidermidis requires accumulation-associated protein (Aap) that contains sequence repeats known as G5 domains, which are responsible for the Zn2+-dependent dimerization of Aap to mediate intercellular adhesion. Antibodies against Aap have been reported to inhibit biofilm accumulation. In the present study, three monoclonal antibodies (MAbs) against the Aap C-terminal single B-repeat construct followed by the 79-aa half repeat (AapBrpt1.5) were generated. MAb18B6 inhibited biofilm formation by S. epidermidis RP62A to 60% of the maximum, while MAb25C11 and MAb20B9 enhanced biofilm accumulation. All three MAbs aggregated the planktonic bacteria to form visible cell clusters. Epitope mapping revealed that the epitope of MAb18B6, which recognizes an identical area within AapBrpt constructs from S. epidermidis RP62A, was not shared by MAb25C11 and MAb20B9. Furthermore, all three MAbs were found to affect both Aap expression and extracellular polymeric substance (EPS, including extracellular DNA and PIA) biosynthesis in S. epidermidis and enhance the cell accumulation. These findings contribute to a better understanding of staphylococcal biofilm formation and will help to develop epitope-peptide vaccines against staphylococcal infections
A new polygenic score for refractive error improves detection of children at risk of high myopia but not the prediction of those at risk of myopic macular degeneration
Background
High myopia (HM), defined as a spherical equivalent refractive error (SER) ≤ −6.00 diopters (D), is a leading cause of sight impairment, through myopic macular degeneration (MMD). We aimed to derive an improved polygenic score (PGS) for predicting children at risk of HM and to test if a PGS is predictive of MMD after accounting for SER.
Methods
The PGS was derived from genome-wide association studies in participants of UK Biobank, CREAM Consortium, and Genetic Epidemiology Research on Adult Health and Aging. MMD severity was quantified by a deep learning algorithm. Prediction of HM was quantified as the area under the receiver operating curve (AUROC). Prediction of severe MMD was assessed by logistic regression.
Findings
In independent samples of European, African, South Asian and East Asian ancestry, the PGS explained 19% (95% confidence interval 17–21%), 2% (1–3%), 8% (7–10%) and 6% (3–9%) of the variation in SER, respectively. The AUROC for HM in these samples was 0.78 (0.75–0.81), 0.58 (0.53–0.64), 0.71 (0.69–0.74) and 0.67 (0.62–0.72), respectively. The PGS was not associated with the risk of MMD after accounting for SER: OR = 1.07 (0.92–1.24).
Interpretation
Performance of the PGS approached the level required for clinical utility in Europeans but not in other ancestries. A PGS for refractive error was not predictive of MMD risk once SER was accounted fo
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Genome-wide association meta-analysis of corneal curvature identifies novel loci and shared genetic influences across axial length and refractive error
Abstract: Corneal curvature, a highly heritable trait, is a key clinical endophenotype for myopia - a major cause of visual impairment and blindness in the world. Here we present a trans-ethnic meta-analysis of corneal curvature GWAS in 44,042 individuals of Caucasian and Asian with replication in 88,218 UK Biobank data. We identified 47 loci (of which 26 are novel), with population-specific signals as well as shared signals across ethnicities. Some identified variants showed precise scaling in corneal curvature and eye elongation (i.e. axial length) to maintain eyes in emmetropia (i.e. HDAC11/FBLN2 rs2630445, RBP3 rs11204213); others exhibited association with myopia with little pleiotropic effects on eye elongation. Implicated genes are involved in extracellular matrix organization, developmental process for body and eye, connective tissue cartilage and glycosylation protein activities. Our study provides insights into population-specific novel genes for corneal curvature, and their pleiotropic effect in regulating eye size or conferring susceptibility to myopia
Reliability of Wide Band Gap Power Electronic Semiconductor and Packaging: A Review
Wide band gap (WBG) power electronic devices, such as silicon carbide metal–oxide–semiconductor field-effect transistors (SiC MOSFETs) and gallium–nitride high-electron-mobility transistors (GaN HEMTs) have been widely used in various fields and occupied a certain share of the market with rapid momentum, owing to their excellent electrical, mechanical, and thermal properties. The reliability of WBG power electronic devices is inseparable from the reliability of power electronic systems and is a significant concern for the industry and for academia. This review attempts to summarize the recent progress in the failure mechanisms of WBG power electronic semiconductor chips, the reliability of WBG power electronic packaging, and the reliability models for predicting the remaining life of WBG devices. Firstly, the typical structures and dominant failure mechanisms of SiC MOSFETs and GaN HEMTs are discussed. This is followed by a description of power electronic packaging failure mechanisms and available packaging materials for WBG power electronic devices. In addition, the reliability models based on physics-of-failure (including time-dependent dielectric breakdown models, stress–strain models, and thermal cycling models), and data-driven models are introduced. This review may provide useful references for the reliability research of WBG power devices
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