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The increasing frequency of extreme rainfall is leading to a rise in groundwater levels in coastal areas, significantly affecting high-speed railway operations. To address this concern, this study developed a 2.5-dimensional finite element model of a coupled track-embankment-ground system based on Biot’s porous media theory to analyze the effect of groundwater level rise on the critical velocity of high-speed railways and vibration responses. The findings reveal a consistent decrease in the critical velocity of high-speed railways with rising groundwater levels. Particularly, the increase in groundwater levels within the embankment significantly influences the critical velocity compared to a similar rise in the foundation’s groundwater level. Furthermore, deformations induced by passing trains significantly increase as groundwater levels rise. Specifically, when the groundwater level rises from the foundation bottom to the subgrade surface, subgrade surface deformation increases by approximately 55%. As trains approach the critical velocity, significant vibration phenomena, known as the “Mach effect,” occur at the foundation surface. Importantly, as groundwater levels rise, the “Mach effect” intensifies. Analyzing the vibrating frequency spectrum of the displacement response demonstrates a substantial increase in vibration amplitude, particularly in the high-frequency region, as groundwater levels rise. This study highlights that the rise in groundwater level not only amplifies vibrations but also extends the propagation of high-frequency vibrations, underscoring the importance of effective embankment waterproofing in controlling track vibrations.

Recently, air quality has become a hot topic due to its profound impact on the quality of the human living environment. This paper selects the tourist city of Dalian as the research object. The concentration and spatial distribution of PM10 and NO2 in the main urban area were analyzed during the peak tourist seasons in summer and winter. Simulations were used to explore the spatial and temporal variation patterns of PM10 and NO2, combining building and road density at different scales to reveal the coupling relationship between individual pollutant components and urban parameters. The results show that the PM10 concentration is high in the center and NO2 is concentrated in the northern district of Dalian City. In an area with a radius of 100 m, the dilution ratio of building density and road density to the concentration of the PM10 pollutants is at least 43%. Still, the concentration of NO2 is only coupled with road density. This study reveals the spatial and temporal variation patterns of PM10 and NO2 in Dalian, and finds the coupling relationship between the two pollutants and building density and road density. This study provides a reference for preventing and controlling air pollution in urban planning.

Objective • Stanford type B aortic dissection is a condition in which the intima of the aorta tears, and TEVAR is an interventional treatment to manage this dissection through intimal repair. To evaluate the medium-term clinical efficacy of endovascular repair (TEVAR) for Aortic dissection and drug Conservative management for Stanford B Aortic dissection aneurysms and further explore whether the former is superior to drug Conservative management in the medium-term efficacy. Methods• The clinical data of 70 patients with stable Standford type B Aortic dissection admitted to our hospital from March 2016 to March 2020 were retrospectively analyzed. They were divided into the treatment group (n = 47) and the control group (n = 23). The control group patients were treated solely with medication, while the treatment group patients were treated with TEVAR on the basis of the control group patients. The treatment efficacy and safety of the two groups of patients were compared and analyzed. All patients will be followed up once a month for 12 months after discharge and every 2 months thereafter (for a total of 3 years). Results • The findings highlight the need to carefully weigh the benefits and harms in the treatment of Stanford type B aortic dissection, especially when considering TEVAR surgery. Future research should focus on reducing postoperative complications to optimize treatment strategies and improve overall patient outcomes. TEVAR surgery significantly reduces hospital mortality, but is also associated with significantly increased postoperative complications, emphasizing the complexity of treatment decisions. This finding provides critical information about weighing the risks and survival benefits of surgery, helping medical teams and patients make informed treatment choices. The hospital mortality rate of patients in the treatment group was 12.77%, while the hospital mortality rate of patients in the control group was 21.74%. The difference between the two groups was statistically significant (P < .05). The incidence of postoperative complications in the treatment group was 23.40%, while the control group did not experience any major complications. The difference between the two groups was statistically significant (P < .05). The mortality rate of patients in the treatment group within 30 days of discharge was 0%, while the mortality rate of patients in the control group within 30 days of discharge was 11.11%. The difference between the two groups was statistically significant (P < .05). The Kaplan Meier curve showed that the survival rates at 3 years of the control and treatment groups were 56.52% and 95.12%, respectively. The log-rank test showed a statistical difference between the two groups. Univariate and multivariate regression analysis showed that postoperative neurological complications (HR = 32.41; P = .00) and preoperative Aortic valve regurgitation (HR = 3.91; P = .00) were risk factors for medium-term death. Conclusion • The TEVAR combination drug is a safe and effective treatment for stable Stanford B Aortic dissection. It can reduce mortality. Compared with drug treatment, it has obvious advantages in medium-term treatment effects. Early rising for high-risk patients can make them have better long-term outcomes. Limitations of the study include its retrospective nature and the use of data from only a single medical center, which may limit the external generalizability of the results [ABSTRACT FROM AUTHOR]