Study on the aging status of insulators based on hyperspectral imaging technology.

The acidic environment is one of the main factors leading to the aging of silicone rubber (SiR) insulators. Aging can reduce the surface hydrophobicity and pollution flashover resistance of insulators, threatening the safe and stable operation of the power grid. Therefore, evaluating the aging state of insulators is essential to prevent flashover accidents on the transmission line. This paper is based on an optical hyperspectral imaging (HSI) technology for pixel-level assessment of insulator aging status. Firstly, the SiR samples were artificially aged in three typical acidic solutions with different concentrations of HNO3, H2SO4, and HCl, and six aging grades of SiR samples were prepared. The HSI of SiR at each aging grade was extracted using a hyperspectral imager. To reduce the calculation complexity and eliminate the interference of useless information in the band, this paper proposes a joint random forest- principal component analysis (RF-PCA) dimensionality reduction method to reduce the original 256-dimensional hyperspectral data to 7 dimensions. Finally, to capture local features in hyperspectral images more effectively and retain the most significant information of the spectral lines, a convolutional neural network (CNN) was used to build a classification model for pixel-level assessment of the SiR's aging state of and visual prediction of insulators' defects. The research method in this paper provides an important guarantee for the timely detection of safety hazards in the power grid.

Endoscopic grading of gastric atrophy on risk assessment of gastric neoplasia: A systematic review and meta-analysis.

BACKGROUND AND AIM: Endoscopic examination of gastric atrophy has been developed to determine the extent of atrophy by identifying the atrophic border of gastric mucosa, but its value in predicting the risk of developing gastric neoplasms is not quantified. Thus, this systematic review and meta-analysis aim to assess the incidence risk of gastric neoplasms on the basis of endoscopic grading of gastric atrophy. METHODS: Two authors independently searched the electronic databases (PubMed, Embase, and the Cochrane Library) from inception through December 31, 2019, without language restriction. The effect size on study outcomes is calculated using random-effects model and presented as risk ratio (RR) with 95% confidence interval (CI). Heterogeneity, publication bias, and quality of included studies were also assessed. RESULTS: Fourteen retrospective studies are identified to perform systematic review and meta-analysis, 11 were cohort studies, and three were cross-sectional research. The pooled RR for developing gastric neoplasms is 3.89 (95% CI 2.92-5.17) among general patients with severe endoscopic atrophy. For patients who underwent endoscopic resection for early gastric neoplasms, nearly two times increased risk of synchronous or metachronous neoplasms is pooled (RR = 1.96, 95% CI 1.39-2.75). In terms of the type of endoscopic atrophy, patients with open-type endoscopic atrophy have a higher risk of gastric cancer development (RR 8.02; 95% CI 2.39-26.88) than those with close type. [Correction added on 22 December 2020, after first online publication: '(RR = 7.27; 95% CI 1.64-32.33)' has been corrected to '(RR 8.02; 95% CI 2.39-26.88)'] CONCLUSIONS: Grading endoscopic atrophy according to the Kimura-Takemoto classification can assess the risk of gastric neoplasia development. Patients with severe or open-type endoscopic gastric atrophy at baseline should undergo rigorous surveillance to early detect premalignant lesions and cancer.

Associations between exposure to cadmium, lead, mercury and mixtures and women's infertility and long-term amenorrhea.

BACKGROUND: Cadmium (Cd), lead (Pb), and mercury (Hg) have been shown to exhibit endocrine disrupting properties. Their effects on women's reproductive health, however, remain elusive. Here, we investigated associations between blood concentrations of Pb, Cd, Hg, and their mixture and infertility and long-term amenorrhea in women aged 20-49 years using the US National Health and Nutrition Examination Survey (NHANES) 2013-2018 cross-sectional survey. METHODS: A total of 1,990 women were included for the analysis of infertility and 1,919 women for long-term amenorrhea. The methods of log-transformation and use of quartiles were used to analyze blood heavy metal concentrations. Statistical differences in the covariates between the outcome groups were evaluated using a chi-squared test for categorical variables and a t-test for continuous variables. Multiple logistic regression models were used to examine the associations. RESULTS: The blood concentrations of Pb and heavy metal mixtures were significantly higher in ever-infertile women than pregnant women, but the concentrations of Cd and Hg were comparable. After full adjustment, multiple logistic regression analyses revealed a significant and dose-dependent positive association between blood Pb concentrations and women's historical infertility, a negative association between Cd and women's long-term amenorrhea, and no associations between Hg and heavy metal mixture and women's infertility or long-term amenorrhea. CONCLUSIONS: Our study suggests that exposure to heavy metals exhibit differential associations with history of infertility and amenorrhea, and Pb may adversely impact women's reproduction and heighten the risks of infertility and long-term amenorrhea.

Timing of Aspirin Use Among Patients With Colorectal Cancer in Relation to Mortality: A Systematic Review and Meta-Analysis.

Background: Exposure of aspirin has been associated with reduced risk of colorectal cancer (CRC) incidence, but aspirin use in relation to CRC patients' mortality remains undetermined. It is necessary to quantify the association between aspirin use and CRC mortality. Methods: Two authors independently searched the electronic databases (PubMed, Embase, and the Cochrane Library) from 1947 through April 25, 2020. All observational studies assessing the association between different timing of aspirin use and CRC mortality were included. The effect size on study outcomes was calculated using random-effect model and presented as risk ratio (RR) with 95% confidence interval (CI). Heterogeneity, publication bias, and quality of included studies were also assessed. Results: A total of 34 studies were included in this systematic review and meta-analysis. Prediagnosis aspirin use was not associated with CRC-specific mortality (RR = 0.91, 95% CI = 0.79 to 1.05) and all-cause mortality (RR = 0.87, 95% CI = 0.57 to 1.31). A statistically significant association between continued aspirin use and improvement in both CRC-specific mortality (RR = 0.76, 95% CI = 0.70 to 0.81) and all-cause mortality (RR = 0.83, 95% CI = 0.74 to 0.93) was observed. Postdiagnosis use of aspirin was associated only with reduced all-cause mortality (RR = 0.80, 95% CI = 0.69 to 0.94). Conclusions: Continued aspirin use before and after CRC diagnosis has the most advantage regarding the improvement of CRC mortality. Nevertheless, further prospective trials and mechanistic studies are highly warranted.