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Abstract Background Short-term exposure to ozone (O3) has been associated with higher stroke mortality, but it is unclear whether this association differs between urban and rural areas. The study aimed to compare the association between short-term exposure to O3 and ischaemic and haemorrhagic stroke mortality across rural and urban areas and further investigate the potential impacts of modifiers, such as greenness, on this association. Methods A multi-county time-series analysis was carried out in 19 counties of Shandong Province from 2013 to 2019. First, we employed generalized additive models (GAMs) to assess the effects of O3 on stroke mortality in each county. We performed random-effects meta-analyses to pool estimates to counties and compare differences in rural and urban areas. Furthermore, a meta-regression model was utilized to assess the moderating effects of county-level features. Results Short-term O3 exposure was found to be associated with increased mortality for both stroke subtypes. For each 10-µg/m3 (lag0-3) rise in O3, ischaemic stroke mortality rose by 1.472% in rural areas and 1.279% in urban areas. For each 0.1-unit increase in the Enhanced Vegetation Index (EVI) per county, the ischaemic stroke mortality caused by a 10-µg/m3 rise in O3 decreased by 0.60% overall and 1.50% in urban areas. Conclusions Our findings add to the evidence that short-term O3 exposure increases ischaemic and haemorrhagic stroke mortality and has adverse effects in urban and rural areas. However, improving greenness levels may contribute to mitigating the detrimental effects of O3 on ischaemic stroke mortality.

BackgroundExcessive sodium and low potassium intake are involved in the development of hypertension. Growing evidence showed that the sodium-to-potassium ratio (Na/K) was significantly associated with blood pressure (BP). However, studies on the dose-response relationship of spot urinary Na/K ratio with hypertension and BP in the general population are scarce, especially in the Chinese population.Materials and methodsData from the post-intervention survey of the Shandong Ministry of Health Action on Salt and Hypertension (SMASH) project was analyzed. Associations between Na/K molar ratio and hypertension prevalence and between Na/K molar ratio and BP indices were analyzed using multivariable logistic and linear regression, respectively, followed by subgroup analysis and interaction analysis. The restricted cubic spline model was used to explore the dose–response relationship. Informed by existing literature, we adjusted for potential confounding factors, including temperature and renal function, to assess the association and dose–response relationship.ResultsThere was a non-linear positive association between Na/K and hypertension (OR:1.09, 95%CI: 1.08–1.11) and a linear positive association between Na/K and systolic BP, diastolic BP, and mean arterial pressure (β 0.53, 95%CI: 0.45–0.60; β 0.36, 95%CI: 0.31–0.41; and β 0.42, 95%CI: 0.36–0.47, respectively). The association was stronger in individuals with hypertension, female patients, those in the 50–59-year age group, and those who were obese. Environmental temperatures had little impact on associations.ConclusionOur findings provide further evidence that the spot urinary Na/K ratio is a simple, useful, and convenient indicator for monitoring salt reduction and potassium increase, which could be used in clinical and public health practices.

Evidence on the association between long-term ozone exposure and greenness exposure and hemorrhagic stroke (HS) is limited, with mixed results. One potential source of this inconsistency is the difference in exposure time metrics. This study aimed to investigate the association between long-term exposure to ambient ozone, greenness, and mortality from HS using exposure metrics at different times. We also examined whether greenness exposure modified the relationship between ozone exposure and mortality due to HS. The study population consisted of 45771 participants aged ≥40 y residing in 20 counties in Shandong Province who were followed up from 2013 to 2019. Ozone exposure metrics (annual mean and warm season) and the normalized difference a measure of greenness exposure, were calculated. The relationship between environmental exposures (ozone and greenness exposures) and mortality from HS was assessed using time-dependent Cox proportional hazards models, and the modification of greenness exposure was examined using stratified analysis with interaction terms. The person-years at the end of follow-up were 90,663. With full adjustments, the risk of death from hemorrhagic stroke increased by 5% per interquartile range increase in warm season ozone [hazard ratio =1.05; 95 % confidence interval: 1.01–1.08]. No clear association was observed between annual ozone and mortality HS. Both the annual and summer NDVI were found to reduce the risk of HS mortality. The relationships were influenced by age, sex, and residence (urban or rural). Furthermore, greenness exposure was shown to have a modifying effect on the relationship between ozone exposure and the occurrence of HS mortality (P for interaction = 0.001). Long-term exposure to warm season O3 was positively associated with HS mortality, while greenness exposure was inversely associated with HS mortality. Greenness exposure may mitigate the negative effects of warm season ozone exposure on HS mortality.

Background: The effects of fine particulate matter (PM2.5) on acute myocardial infarction (AMI) have been widely recognized. However, no studies have comprehensively evaluated future PM2.5-attributed AMI burdens under different climate mitigation and population change scenarios. We aimed to quantify the PM2.5-AMI association and estimate the future change in PM2.5-attributed AMI incident cases under six integrated scenarios in 2030 and 2060 in Shandong Province, China. Methods: Daily AMI incident cases and air pollutant data were collected from 136 districts/counties in Shandong Province from 2017 − 2019. A two-stage analysis with a distributed lag nonlinear model was conducted to quantify the baseline PM2.5-AMI association. The future change in PM2.5-attributed AMI incident cases was estimated by combining the fitted PM2.5-AMI association with the projected daily PM2.5 concentrations under six integrated scenarios. We further analyzed the factors driving changes in PM2.5-related AMI incidence using a decomposition method. Results: Each 10 μg/m3 increase in PM2.5 exposure at lag05 was related to an excess risk of 1.3 % (95 % confidence intervals: 0.9 %, 1.7 %) for AMI incidence from 2017 − 2019 in Shandong Province. The estimated total PM2.5-attributed AMI incident cases would increase by 10.9−125.9 % and 6.4–244.6 % under Scenarios 1 − 3 in 2030 and 2060, whereas they would decrease by 0.9–5.2 % and 33.0–46.2 % under Scenarios 5 – 6 in 2030 and 2060, respectively. Furthermore, the percentage increases in PM2.5-attributed female cases (2030: −0.3 % to 135.1 %; 2060: −33.2 % to 321.5 %) and aging cases (2030: 15.2–171.8 %; 2060: −21.5 % to 394.2 %) would wholly exceed those in male cases (2030: −1.8 % to 133.2 %; 2060: −41.1 % to 264.3 %) and non-aging cases (2030: −41.0 % to 45.7 %; 2060: −89.5 % to −17.0 %) under six scenarios in 2030 and 2060. Population aging is the main driver of increased PM2.5-related AMI incidence under Scenarios 1 − 3 in 2030 and 2060, while improved air quality can offset these negative effects of population aging under the implementation of the carbon neutrality and 1.5 °C targets. Conclusion: The combination of ambitious climate policies (i.e., 1.5 °C warming limits and carbon neutrality targets) with stringent clean air policies is necessary to reduce the health impacts of air pollution in Shandong Province, China, regardless of population aging.

Qinghai is located in a permafrost region, which belongs to the continental climate zone of the the Qinghai-Tibet Plateau. At the same time, freezing-thawing cycles are common destructive factors for roadbeds and foundations. In order to examine the effects of freezing-thawing cycles on actual projects in Qinghai and reveal the mechanisms of freezing-thawing cycles on damage of the projects, the freezing-thawing cycle test, unconfined compressive strength test and electron microscope scanning test of the undisturbed loess and remolded loess in the Xining area of Qinghai are conducted to analyze the influence of different freezing-thawing temperatures and different freezing-thawing cycles on the strength and microstructure of the undisturbed loess and remolded loess. The results show that when the loess undergoes 0-6 freezing-thawing cycles, the strength of the undisturbed loess and remolded loess gradually decreases. After 8-10 freezing-thawing cycles, the unconfined compressive strength of the loess first increases and then tends to be basically stable. The strength of the undisturbed loess decreases with the decrease of the freezing and thawing temperature. However, the strength of the remolded loess first increases and then decreases with the decrease of temperature. From a microscopic point of view, the decrease in freezing-thawing temperature and the increase in the number of freezing-thawing cycles both lead to the decomposition of large loess particles into small particles, and the arrangement of the particles has changed. The results are of reference value for actual project construction and construction in the Xining area of Qinghai.

The linear motor feeding system is a typical electromechanical coupling system. Conventional characteristic analyses of electromechanical coupling often overlook the influence of flexible deformation in critical components of the linear motor feeding system. Moreover, when employing genetic algorithms to optimize servo system PID control parameters, slow convergence, nonconvergence, or premature convergence problems may arise. To address these issues, this paper proposes a new performance optimization method for a linear motor feeding system. The method uses a combination of “multi-body theory + finite element” to accurately account for the flexible deformation of critical components of the feeding system, establishes a rigid–flexible electromechanical coupling model of the linear motor feeding system, and optimizes the PID parameters of the established model with an improved adaptive genetic algorithm. Simulation results demonstrate that, when utilizing an adaptive genetic algorithm to optimize the rigid–flexible electromechanical coupling model and a control system model that disregards flexible body deformation, the system achieves stability in 0.02 s and 0.027 s with overshoots of 13% and 27%, respectively. These outcomes confirm the accuracy and importance of considering flexible body deformation in the optimization performance of a linear motor feeding system. At the same time, the time required to reach the steady state of the rigid–flexible electromechanical coupling model optimized by the adaptive genetic algorithm is shortened from 0.035 s to 0.02 s. The sinusoidal signal response curve of the optimized system does not exhibit any peak overshoot compared with that of the nonoptimized system, and the response speed is also faster. These results demonstrate the effectiveness of the rigid–flexible electromechanical coupling model optimized by the nonlinear adaptive genetic algorithm. The displacement response curves of the linear motor feeding system under different workbench loads are obtained through experiments and compared with those obtained from simulations to verify the established model and the correctness of the proposed method.

BackgroundLocal governments in China took restrictive measures after the outbreak of COVID-19 to control its spread, which unintentionally resulted in reduced anthropogenic emission sources of air pollutants. In this study, we intended to examine the effects of the COVID-19 lockdown policy on the concentration levels of particulate matter with aerodynamic diameters of ≤1 μm (PM1), ≤2.5 μm (PM2.5), and ≤10 μm (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and carbon monoxide (CO) and the potential subsequent reductions in the incidence of ischemic and hemorrhagic stroke in Shandong Province, China.MethodsA difference-in-difference model combining the daily incidence data for ischemic and hemorrhagic stroke and air pollutant data in 126 counties was used to estimate the effect of the COVID-19 lockdown on the air pollutant levels and ischemic and hemorrhagic stroke incident counts. The avoided ischemic stroke cases related to the changes in air pollutant exposure levels were further estimated using concentration-response functions from previous studies.ResultsThe PM1, PM2.5, PM10, NO2, and CO levels significantly decreased by −30.2, −20.9, −13.5, −46.3, and −13.1%, respectively. The O3 level increased by 11.5% during the lockdown compared with that in the counterfactual lockdown phase of the past 2 years. There was a significant reduction in population-weighted ischemic stroke cases (−15,315, 95% confidence interval [CI]: −27,689, −2,942), representing a reduction of 27.6% (95% CI: −49.9%, −5.3%). The change in the number of hemorrhagic stroke cases was not statistically significant. The total avoided PM1-, PM2.5-, PM10-, NO2-, and CO–related ischemic stroke cases were 739 (95% CI: 641, 833), 509 (95% CI: 440, 575), 355 (95% CI: 304, 405), 1,132 (95% CI: 1,024, 1,240), and 289 (95% CI: 236, 340), respectively.ConclusionThe COVID-19 lockdown indirectly reduced the concentration levels of PM1, PM2.5, PM10, NO2, and CO and subsequently reduced the associated ischemic stroke incidence. The health benefits due to the lockdown are temporary, and long-term measures should be implemented to increase air quality and related health benefits in the post-COVID-19 period.

The parameters of the constitutive model, the creep model, and the wetting model of materials of the Nuozhadu high earth-rockfill dam were back-analyzed together based on field monitoring displacement data by employing an intelligent back-analysis method. In this method, an artificial neural network is used as a substitute for time-consuming finite element analysis, and an evolutionary algorithm is applied for both network training and parameter optimization. To avoid simultaneous back-analysis of many parameters, the model parameters of the three main dam materials are decoupled and back-analyzed separately in a particular order. Displacement back-analyses were performed at different stages of the construction period, with and without considering the creep and wetting deformations. Good agreement between the numerical results and the monitoring data was obtained for most observation points, which implies that the back-analysis method and decoupling method are effective for solving complex problems with multiple models and parameters. The comparison of calculation results based on different sets of back-analyzed model parameters indicates the necessity of taking the effects of creep and wetting into consideration in the numerical analyses of high earth-rockfill dams. With the resulting model parameters, the stress and deformation distributions at completion are predicted and analyzed.

BACKGROUND: It has been reported that the prevalence of chronic diseases is high among old people and they have poor chronic diseases knowledge. This study was therefore designed to evaluate the awareness rate of chronic diseases knowledge among people aged over 60 years, to explore its related factors and to provide evidence for future health education. METHODS: A cross-sectional study was conducted from April to August in 2011. People aged 60 years and above from 3 communities in Jinan were selected by cluster sampling. Nine hundred and twenty five participants were interviewed face-to-face using a structured questionnaire. RESULTS: The awareness rates of chronic diseases knowledge varied from 29.5% to 90.2%. Four healthy lifestyles including quitting smoking and less drinking, keeping broad-minded, maintaining balanced diet and moderate physical activity were best known (from 86.3% to 90.2%). The least known knowledge were 2 complications of hypertension: nephropathy (29.5%) and retinopathy (37.2%). Participants with the following characteristics or behaviors were more likely to have higher chronic diseases knowledge: younger age, female, Han Chinese, higher level of education, having health insurance, participating in societies, having family history of chronic diseases, frequently gathering with friends/relatives, usually going to provincial hospitals/hospitals affiliated with medical universities, usually going to municipal hospitals and usually going to community health center/station. CONCLUSIONS: Old people in Jinan had incomplete chronic diseases knowledge and the overall awareness rate was not high. The older people's chronic diseases knowledge should be improved and health education programs should target males, older people with lower educational level, having no health insurance, having no family history of chronic diseases, participating in no societies, and less frequently gathering with friends/relatives. Also, lower level medical facilities should improve their skills of health education.

The variation of stress-strain state induces changes in the permeability of clayey soil and then affects the properties of seepage and consolidation. In previous studies, variations of the permeability of soil in shear process were mainly neglected, and there were no reasonable descriptions of the permeability in such a condition. To study the variation of the hydraulic conductivity of clayey soil in shear process, new triaxial seepage equipment was designed by changing the conventional triaxial apparatus. Based on a series of tests under different confining pressures carried out by this equipment, the influences of the stress-strain state of clayey soil on hydraulic conductivity were investigated. Furthermore, a mathematical model for the hydraulic conductivity of clayey soil under the condition of large shear deformation was proposed. The comparison between the seepage test results and the calculated values of the proposed model indicates that the mathematical model can calibrate the effects of the void ratio and the mesostructure on the hydraulic conductivity of soil in shear process very well. [ABSTRACT FROM AUTHOR]

A consolidation analysis method for an earth-rockfill dam based on the coupling of physical state, stress deformation, and seepage was established. In this method, a permeability coefficient model considering physical state and shear stress level was introduced, and it was integrated with Biot's consolidation theory to simulate the coupling relationship. Taking the Nuozhadu high earth-rockfill dam as an example, a parameter back-analysis method using a neural network and evolutionary algorithm was applied to back-analyze the permeability coefficient model parameters of the core material based on observation data of pore water pressure in the dam. Then, consolidation numerical analyses were performed by using the back-analyzed parameters and the constant permeability measured in situ, respectively. The spatial and temporal distribution of pore water pressure calculated by the back-analyzed parameters coincided quite well with the monitoring data during construction and operation. However, the numerical results with constant permeability are different from the observed values, which indicates that the permeability coefficient model and the consolidation analysis method can be applied effectively, reasonably, and necessarily to numerical sim- ulations for high earth-rockfill dams. [ABSTRACT FROM AUTHOR]