Association between triglyceride glucose index and risk of cerebrovascular disease: systematic review and meta-analysis.

BACKGROUND: The triglyceride glucose (TyG) index, which is a new surrogate indicator of insulin resistance (IR), is thought to be associated with many diseases, such as cardiovascular disease, but its relationship with cerebrovascular disease is still controversial. METHODS: The PubMed, EMBASE, Cochrane Library, Web of Science and Medline databases were searched until March 2022 to evaluate the association between the TyG index and cerebrovascular disease risk. A random‒effects model was used to calculate the effect estimates and 95% confidence intervals (CIs). RESULTS: A total of 19 cohort studies and 10 case‒control/cross‒sectional studies were included in our study, which included 11,944,688 participants. Compared with a low TyG index, a higher TyG index increased the risk of cerebrovascular disease (RR/HR = 1.22, 95% CI [1.14, 1.30], P< 0.001; OR = 1.15, 95% CI [1.07, 1.23], P< 0.001). Furthermore, the results of the dose-response analysis of the cohort study demonstrated that the risk of cerebrovascular disease increased by 1.19 times per 1 mg/dl increment of the TyG index (relative risk = 1.19, 95% CI [1.13,1.25], P< 0.001). CONCLUSION: TyG index is related to cerebrovascular disease. More data and basic research are needed to confirm the association.

Polarization measurement accuracy analysis and improvement methods for the directional polarimetric camera.

The directional polarimetric camera (DPC) is a remote-sensing instrument for the characterization of atmospheric aerosols and clouds by simultaneously conducting spectral, angular, and polarimetric measurements. Polarization measurement accuracy is an important index to evaluate the performance of the DPC and mainly related to the calibration accuracy of instrumental parameters. In this paper, firstly, the relationship between the polarization measurement accuracy of DPC and the parameter calibration errors caused by the nonideality of the components of DPC are analyzed, and the maximum polarization measurement error of DPC in the central field of view and edge field of view after initial calibration is evaluated respectively. Secondly, on the basis of the radiometric calibration of the DPC onboard the GaoFen-5 satellite in an early companion paper [Opt. Express2813187 (2020)10.1364/OE.391078], a series of simple and practical methods are proposed to improve the calibration accuracy of the parameters-the diattenuation of the optics, absolute azimuth angle, and relative transmission corresponding to each pixel, thereby improving the polarization measurement accuracy of DPC. The calibration results show that, compared with the original methods, the accuracy of the diattenuation of the optics, relative azimuth angle, and relative transmission of three polarized channels obtained with the improved methods are improved from ±1%, 0.1 degree and ±2% to ±0.4%, 0.05 degree and ±0.2%, respectively. Finally, two verification experiments based on a non-polarized radiation source and a polarizing system were carried out in the laboratory respectively to verify the improvement of the parameters modified by the proposed methods on the polarization measurement accuracy of the DPC to be boarding the GaoFen-5 (02) satellite. The experimental results show that when the corrected parameters were employed, the average error in measuring the degree of linear polarization of non-polarized light source for all pixels in the three polarized bands and the maximum deviation of the degree of linear polarization between the values set by the polarizing system and the values measured by the DPC at several different field of view angles for each polarized spectral band are obviously reduced. Both the mean absolute errors and the root mean square errors of the degree of linear polarization obtained with the corrected parameters are much lower than those obtained with the original parameters. All of these prove the effectiveness of the proposed methods.

Polarimetric imaging detection using a convolutional neural network with three-dimensional and two-dimensional convolutional layers.

Polarimetric imaging detection is a relatively new and largely undeveloped field. Although convolutional neural networks (CNNs) have achieved great success in two-dimensional (2D) normal intensity images in the field of target detection, traditional CNN methods have not been widely applied to optical polarimetric images, and they cannot take full advantage of the connection between different polarimetric images. To solve this problem, three-dimensional (3D) convolutions are adopted to consider the relationship between S0, S1, and S2 images as a third dimension. Based on the 3D convolutions, a CNN with 3D and 2D convolutional layers is introduced to further improve the success rate of target detection with limited polarimetric images. The evaluations in different natural backgrounds reveal that the proposed method achieves higher detection accuracy than that of two traditional methods for comparison.

Geometric calibration method based on a two-dimensional turntable for a directional polarimetric camera.

The directional polarimetric camera (DPC) is a polarization sensor with ultra-wide-angle and low-distortion imaging characteristics. Geometric calibration is usually the first essential step before remote sensing satellites are launched. In this paper, a geometric calibration method based on a two-dimensional turntable and a rotation matrix with high precision, simple operation, and wide application range is proposed for the directional polarimetric camera. Instead of precisely adjusting the position of the sensor on the turntable, the method effectively eliminates the errors caused by the mechanical axis of the turntable and the optical axis of the sensor not being adjusted to the same direction through the rotation transformation of the coordinate system. The geometric calibration experiments of the directional polarimetric camera were carried out with the method of Chen et al. [Optik121, 486 (2010)10.1016/j.ijleo.2008.08.004OTIKAJ0030-4026] and the proposed method. The experimental results showed the calibration residual of the proposed method was less than 0.1 pixel while Chen's method was 0.3 pixel. The mean reprojection error and root mean square error of the proposed method were reduced to 0.06352 pixel and 0.06961 pixel, respectively. The geometric calibration parameters obtained by the proposed method were used for geometric correction of the in-orbit images of the DPC, and the results also prove the effectiveness and superiority of the proposed method.

Bandwidth correction of spectral measurement based on Levenberg-Marquardt algorithm with improved Tikhonov regularization.

Spectroscopic data often suffers from spectral distortions due to the broadening effects of the spectrometer. In this paper, the issue of bandwidth correction is transformed into a multiparameter optimization problem, and an improved bandwidth correction method based on the Levenberg-Marquardt algorithm with improved Tikhonov regularization is presented. Example LED, Raman, and compact fluorescent lamp spectra were corrected with the proposed method, the Richardson-Lucy method, and the maximum a posterior method, and the correction errors and runtimes under the same stopping conditions of each method were compared. The experimental results show that the proposed method can be applied to different spectra with excellent correction.

Directional polarimetric camera stray light analysis and correction.

The directional polarimetric camera is a polarization sensor that offers an ultrawide angle and low-distortion imaging. Stray light is one of the important factors affecting the accuracy of its polarization measurement. In this paper, the stray light of the directional polarimetric camera is first divided into local stray light and global stray light according to the characteristics of its optical system, and the causes and characteristics of the two kinds of stray light are analyzed. Second, a novel deconvolution method is proposed to correct the local stray light, and the matrix method is extended to a 2D form to correct the global stray light. Finally, image acquisition and stray light correction laboratory experiments of integrating a sphere light source were carried out. The experimental results show that the proposed correction methods can effectively suppress more than 94% of the stray light of the directional polarimetric camera.

Correlation between intensity fluctuations of electromagnetic waves scattered from a spatially quasi-homogeneous, anisotropic medium.

Within the validity of the first-order Born approximation, expressions are derived for the correlation between intensity fluctuations (CIF) of an electromagnetic plane wave scattered from a spatially quasi-homogeneous (QH), anisotropic medium. Upon establishing the correlation matrix of the scattering potential of the medium, we show that the CIF is the summation of Fourier transforms of the strengths and normalized correlation coefficients (NCCs) of the scattering potential matrix. Numerical results reveal that the CIF is susceptible to the effective width and correlation length of the medium, and degree of polarization of the incident electromagnetic wave. Our study not only extends the current knowledge of the CIF of a scattered field but also provides an important reference to the study of high-order intensity correlations of light scattered from a spatially anisotropic medium.

[Multi-spectral measurement of Basic oxygen furnace flame temperature].

A multi-wavelength analysis method is introduced to measure the temperature of basic oxygen furnace flame. In this study, USB4000 spectrometer was applied to obtain radiation spectrum of flame within wavelength range 200-1 100 nm, from which the flame temperature and monochromatic emissivity was derived by Levenberg-Marquart modeling method. Wavelet neural network was applied to process the spectral measurement data, which could cancel the assumption model of emissivity and wavelengths. It is a kind of valid method to acquire the true temperature and spectral emissivity. Each neuron in the hidden layer of a feed-forward network is a combination of the sigmoidal activation function (SAF) and morlet wavelet activation function (WAF). The output of the hidden neuron is the product of the output from these two activation functions.

Association between triglyceride glucose index and risk of cancer: A meta-analysis.

Background: Triglyceride glucose (TyG) index as a more convenient and reliable predictor of insulin resistance (IR) is thought to be associated with many diseases, but its relationship with cancer remains unclear. Methods: The meta-analysis was conducted to evaluate the effects of TyG index on cancer risk utilizing the available evidence. PubMed, EMBASE, Medline, Cochrane Library and Web of Science were searched from their inception up to July 2022. A random-effects model was used to calculate the effect estimates and 95% confidence intervals (CIs). Results: A total of 6 observational studies met our inclusion criteria, which including 992292 participants. The meta-analysis indicated that the higher TyG index increased cancer risk compared to the lower TyG index group (total effect size =1.14, 95% CI [1.08, 1.20], P<0.001). Conclusions: Our meta-analysis found that higher TyG index may increase the risk of cancer. More prospective cohort studies and basic research are warranted to verify the relationship.

The Diagnostic and Prognostic Value of the Triglyceride-Glucose Index in Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD): A Systematic Review and Meta-Analysis.

Metabolic dysfunction-associated fatty liver disease (MAFLD) has been related to a series of harmful health consequences. The triglyceride-glucose index (TyG index) appears to be associated with MAFLD. However, no consistent conclusions about the TyG index and incident MAFLD have been reached. PubMed, MEDLINE, Web of Science, EMBASE and the Cochrane Library were searched. Sensitivities, specificities and the area under the receiver operating characteristic (AUC) with a random-effects model were used to assess the diagnostic performance of the TyG index in NAFLD/MAFLD participants. Potential threshold effects and publication bias were evaluated by Spearman's correlation and Deeks' asymmetry test, respectively. A total of 20 studies with 165725 MAFLD participants were included. The summary receiver operator characteristic (SROC) curve showed that the sensitivity, specificity and AUC were 0.73 (0.69−0.76), 0.67 (0.65, 0.70) and 0.75 (0.71−0.79), respectively. Threshold effects (r = 0.490, p < 0.05) were confirmed to exist. Subgroup analyses and meta-regression showed that some factors including country, number of samples, age and disease situation were the sources of heterogeneity (p < 0.05). Our meta-analysis suggests that the TyG index can diagnose and predict MAFLD patients with good accuracy. The number of studies remains limited, and prospective studies are needed.