A continuous and long-term in-situ stress measuring method based on fiber optic. Part I: Theory of inverse differential strain analysis

A method for in-situ stress measurement via fiber optics was proposed. The method utilizes the relationship between rock mass elastic parameters and in-situ stress. The approach offers the advantage of long-term stress measurements with high spatial resolution and frequency, significantly enhancing the ability to measure in-situ stress. The sensing casing, spirally wrapped with fiber optic, is cemented into the formation to establish a formation sensing nerve. Injecting fluid into the casing generates strain disturbance, establishing the relationship between rock mass properties and treatment pressure.Moreover, an optimization algorithm is established to invert the elastic parameters of formation via fiber optic strains. In the first part of this paper series, we established the theoretical basis for the inverse differential strain analysis method for in-situ stress measurement, which was subsequently verified using an analytical model. This paper is the fundamental basis for the inverse differential strain analysis method.

Body mass index,waist circumference,and cardiometabolic risk factors in young and middle-aged Chinese women

Objective: To assess the associations between body mass index (BMI), waist circumference (WC), and cardiometabolic risk factors in young and middle-aged Chinese women. Methods: A total of 3011 women (1938 young women, 1073 middle-aged women), who visited our health care center for a related health checkup, were eligible for study. BMI and WC were measured. The subjects were divided into normal and overweight/obesity groups based on BMI, and normal and abdominal obesity groups based on WC. Cardiometabolic variables included triglyceride (TG), high density lipoprotein cholesterol (HDL-C), fasting blood glucose (FBG), homeostasis model assessment of insulin resistance (HOMA-IR), and blood pressure (BP). Results: The prevalence of overweight/obesity was significantly higher in middle-aged women (32.4%) than in young women (12.0%). The prevalence of abdominal obesity was also higher in middle-aged women (60.3%) than in young women (36.2%). There were significant differences in the comparison of all related cardiometabolic variables between different BMI (or WC) categories in young and middle- aged women groups, respectively. After adjustment for age, partial correlation analysis indicated that both BMI and WC were correlated significantly with all related cardiometabolic variables. After adjustment for age and WC, although the correlation coefficient r′was attenuated, BMI was still correlated significantly with all related cardiometabolic variables in young and middle-aged women. After adjustment for age and BMI, partial correlation analysis showed that WC was correlated significantly with TG, FBG, HOMA-IR, and HDL-C in young women and significantly with TG, HOMA-IR, and HDL-C in middle-aged women. Conclusions: The prevalence of overweight/obesity and abdominal obesity was high in Chinese young and middle-aged women. BMI was a better predictor of cardiovascular disease and diabetes than WC in young and middle-aged women, and moreover, measurement of both WC and BMI may be a better predictor of cardiovascular disease and diabetes mellitus than BMI or WC alone.