Search Results (149)

Space gravitational wave detection, which could help humanity explore the mysteries of the universe, is a significant objective in the scientific world today, and several different countries and scientific groups have organized programs targeting its realization. The telescope for gravitational wave detection is a crucial component in the detection satellite, as it is the means of receiving and transmitting the interferometric laser beam; therefore, its structural design is very significant. This paper focuses on the telescope in the TianQin program. First, a structural design scheme is given based on a five-mirror optical system Then, some of the component’s parts are refined to improve its mechanical performance. Finally, a mechanical simulation analysis is performed to verify its reliability and feasibility during the rocket launch. The results reveal that the presented structural design scheme for the telescope is both safe and viable. Full article

Background: This study aims to investigate the electrocardiographic (ECG) alterations associated with hypercalcemia, focusing on characteristic T-wave alterations as potential diagnostic indicators. Methods: Utilizing a retrospective observational design, we analyzed ECG data from 64 hypercalcemic patients and a control group of 956 normocalcemic individuals. Results: Our findings reveal that 78.13% of hypercalcemic patients exhibited characteristic T-wave alterations, compared to only 14.64% in the control group (p < 0.001). Additionally, hypercalcemic patients demonstrated significantly shorter mean QT, QTc, and QTm intervals (QT: 340.5 ± 15.4 vs. 380.6 ± 75.5, QTc: 404.2 ± 78.4 vs. 415.7 ± 57.1, QTm: 226.6 ± 23.4 vs. 270.6 ± 27.0; all p < 0.01). Notably, the sensitivity, specificity, and accuracy of T-wave alterations for diagnosing hypercalcemia were 78.12%, 97.28%, and 96.08%, respectively, outperforming QT shortening (sensitivity: 48.43%, specificity: 76.99%). Conclusions: These results indicate that characteristic T-wave alterations are not only prevalent but also provide a reliable diagnostic tool for hypercalcemia, suggesting that integrating ECG analysis into routine clinical practice may enhance early detection and management of this condition. Full article

Sediment plumes threatening benthic ecosystems are one of the environmental hazards associated with seafloor interventions such as bottom trawling, cabling, dredging, and marine mining operations. This study focuses on sediment plume release from hypothetical future deep-sea mining activities, emphasizing its interaction with turbulent ocean currents in regions characterized by complex seafloor topography. In such environments, turbulent lee waves may significantly enhance the scattering of released sediments, pointing to the clear need for appropriate impact assessment frameworks. Global-scale models are limited in their ability to resolve sufficiently high Reynolds numbers to accurately represent turbulence generated by seafloor topography. To overcome these limitations and effectively assess lee wave dynamics, models must incorporate the full physics of turbulence without simplifying the Navier–Stokes equations and must operate with significantly finer spatial discretization while maintaining a domain large enough to capture the full topographic signal. Considering a seamount in the Lofoten Basin of the Norwegian Sea as an example, we present a novel numerical analysis that explores the interplay between lee wave turbulence and sediment plume dispersion using a high-resolution Large Eddy Simulation (LES) framework. We show that the turbulence occurs within semi-horizontal channels that emerge beyond the topographic highs and extend into sheet-like tails close to the seafloor. In scenarios simulating sediment release from various sites on the seamount, our model predicts distinct behavior patterns for different particle sizes. Particles with larger settling velocities tend to deposit onto the seafloor within 50–200 m of release sites. Conversely, particles with lower settling velocities are more susceptible to turbulent transport, potentially traveling greater distances while experiencing faster dilution. Based on our scenarios, we estimate that the plume concentration may dilute below 1 ppm at about 2 km distance from the release site. Although our analysis shows that mixing with ambient seawater results in rapid dilution to low concentrations, it appears crucial to account for the effects of topographic lee wave turbulence in impact assessments related to man-made sediment plumes. Our high-resolution numerical simulations enable the identification of sediment particle size groups that are most likely affected by turbulence, providing valuable insights for developing targeted mitigation strategies. Full article

An important goal in cardiology and other fields is to identify and control dynamic spiral wave patterns in reaction–diffusion partial differential equations. This research focuses on the Barkley model. The spiral wave motion is controlled and suppressed within the Euclidean group rather than through Euclidean symmetry by applying a controller equation. The eigenfunctions associated with the left eigenspace of the adjoint linear equation can be used to characterize the drift or movement of the spiral wave tip trajectory when the system is perturbed. These eigenfunctions provide details regarding how the spiral wave reacts to disruptions. Perturbations to the Barkley system are examined by applying control functions and calculating the principle eigenvalue numerically. The left eigenfunctions of the Barkley equation are determined by solving the left problem associated with the $2\mathrm{D}$ Barkley equation and a $1\mathrm{D}$ dynamical controller. In addition, the control function can be used to suppress the periodic and meandering regimes of the system. In this work, the focus is on the periodic regime. Full article

This study presents an experimental analysis of high-pressure liquid and gas gate valve leakage under multiple operating conditions, based on the variation patterns of ultrasonic signals. Focusing on a multi-physics field analysis of gate valve internal leakage and corresponding experiments, this research illustrates the acoustic wave characteristics of gate valves across diverse working media, pressures, internal leakage defect sizes, and valve diameters. By drawing upon both fluid mechanics and acoustics theory, an analytical approach suited to high-pressure gate valve leakage issues is devised. Separate high-pressure gate valve leakage test platforms for liquid and gas environments were designed and constructed, enabling 126 groups of tests under varying conditions, which include one measurement per condition of the valve size, defect size, and pressure value. These experiments examine the quantitative correlation of internal leakage flow rates and ultrasonic signal measurements under different situations. In addition, the distinct behaviors and principles exhibited by high-pressure liquid gate valves and gas gate valves are compared. The findings provide theoretical and technical support for quantifying high-pressure gate valve leakage. The study analyzes the theoretical basis for the generation of ultrasonic signals from valve internal leakage, providing specific experimental data under various operating conditions. It explains the various observations during the experiments and their principles. The conclusions of this research have practical engineering value and provide important references for future studies. Full article

Background: Children diagnosed with Speech Sound Disorders (SSDs) encounter difficulties in speech perception, especially when listening in the presence of background noise. Recommended protocols for auditory processing evaluation include behavioral linguistic and speech processing tests, as well as objective electrophysiological measures. The present study compared the auditory processing profiles of children with SSD and typically developing (TD) children using a battery of behavioral language and auditory tests combined with auditory evoked responses. Methods: Forty (40) parents of 7–10 years old Greek Cypriot children completed parent questionnaires related to their children’s listening; their children completed an assessment comprising language, phonology, auditory processing, and auditory evoked responses. The experimental group included 24 children with a history of SSDs; the control group consisted of 16 TD children. Results: Three factors significantly differentiated SSD from TD children: Factor 1 (auditory processing screening), Factor 5 (phonological awareness), and Factor 13 (Auditory Brainstem Response—ABR wave V latency). Among these, Factor 1 consistently predicted SSD classification both independently and in combined models, indicating strong ecological and diagnostic relevance. This predictive power suggests real-world listening behaviors are central to SSD differentiation. The significant correlation between Factor 5 and Factor 13 may suggest an interaction between auditory processing at the brainstem level and higher-order phonological manipulation. Conclusions: This research underscores the diagnostic significance of integrating behavioral and physiological metrics through dimensional and predictive methodologies. Factor 1, which focuses on authentic listening environments, was identified as the strongest predictor. These results advocate for the inclusion of ecologically valid listening items in the screening for APD. Poor discrimination of speech in noise imposes discrepancies between incoming auditory information and retained phonological representations, which disrupts the implicit processing mechanisms that align auditory input with phonological representations stored in memory. Speech and language pathologists can incorporate pertinent auditory processing assessment findings to identify potential language-processing challenges and formulate more effective therapeutic intervention strategies. Full article

Background/Objectives: Despite growing interest in oral frailty as a public health issue, no nationwide study has assessed regional differences in oral frailty awareness, and the factors associated with such differences remain unclear. This study investigated regional differences in oral frailty awareness among older adults in Japan and identified the associated individual- and municipal-level factors, focusing on local policy measures and community-based oral health programs. Methods: A cross-sectional analysis was conducted using data from the 2022 wave of the Japan Gerontological Evaluation Study. The analytical sample comprised 20,330 community-dwelling adults aged ≥65 years from 66 municipalities. Awareness of oral frailty was assessed via self-administered questionnaires. Individual- and municipal-level variables were analyzed using multilevel Poisson regression models to calculate prevalence ratios (PRs). Results: Awareness of oral frailty varied widely across municipalities, ranging from 15.3% to 47.1%. Multilevel analysis showed that being male (PR: 1.10), having ≤9 years (PR: 1.10) or 10 to 12 years of education (PR: 1.04), having oral frailty (PR: 1.04), and lacking civic participation (PR: 1.06) were significantly associated with lack of awareness. No significant associations were found with municipal-level variables such as dental health ordinances, volunteer training programs, or population density. Conclusions: The study found substantial regional variation in oral frailty awareness. However, this variation was explained primarily by individual-level characteristics. Public health strategies should focus on enhancing awareness among socially vulnerable groups—especially men, individuals with low educational attainment, and those not engaged in civic activities—through targeted interventions and community-based initiatives. Full article

Traditionally, disaster research has focused on well-being consequences or socio-economic effects, often overlooking the association between disaster-brought life changes (i.e., transition) and mental health. Therefore, in this online longitudinal survey, we aimed to evaluate the long-term transitional impact of the flood in Western Germany and the wildfire in British Columbia, Canada, both of which happened during the summer of 2021. Additionally, we aimed to examine the relationships among these disaster-specific transitions and mental health, as well as feelings of being abandoned by the community and government. In this multi-site, multi-disaster study, 48 BC and 41 Western Germany adults were first assessed in 2021, then reassessed in 2022. During both waves, respondents completed the 12-item TIS, the 21-item DASS, the 8-item PCL, and the 2-item feeling of abandonment instrument (community and government). Results indicated that (a) the Germany flood produced higher material and psychological change in 2021 than in 2022; (b) the BC fire produced higher psychological change in 2021 than 2022, but produced modest material change in both time points; (c) the BC-fire group reported greater mental distress in 2021 than 2022, the Germany-flood group reported moderate-to-severe mental distress in both waves, and neither group experienced PTSD-like symptoms; (d) in both groups, evacuees experienced more change and distress than non-evacuees; (e) BC-fire evacuees and Germany-flood non-evacuees indicated that they felt more abandoned by their community than their government; and (f) over time, only psychological changes were reliably associated with distress in both groups. We speculated that following disasters, people’s mental health was largely shaped by the levels of disaster-induced life changes, particularly psychological changes that unfold over time. Full article

This study experimentally evaluates the survivability and hydrodynamic performance of a moored oscillating water column (OWC) wave energy converter (WEC) subjected to extreme cyclonic wave conditions emulating tropical cyclone Oma (2019). Laboratory tests recreated realistic cyclonic sea states using focused wave groups through the NewWave theory, combining singular and embedded focused waves within irregular seas to simulate extreme crests, troughs, and transient slamming events. Three mooring systems, including catenary, vertical-taut, and taut with 45° tendons, were tested to quantify their influence on structural response, chamber pressures, mooring tensions, and motion dynamics. The results revealed a critical trade-off: mooring configurations optimised for energy capture efficiency (e.g., taut systems) exhibited reduced survivability during extreme waves, while survivability-focused designs (e.g., catenary) compromised operational performance. Slamming pressures and transient loads were highly sensitive to wave group and mooring stiffness, with vertical taut systems experiencing the largest peak tensions. By integrating localised slamming pressure data with global mooring load measurements, this work provides a novel framework for balancing energy production and storm resilience in OWC design. Full article

Degradation of polyethylene and polystyrene was studied theoretically using reactive molecular dynamics based on the ReaxFF force field. The degradation reactions were carried out on nanoparticles (approximately 2 nm in diameter) composed of ideal low-density polyethylene and polystyrene in the presence of water. The reactions leading to degradation were triggered by applying a shock wave through the simulation box. This approach allowed the energy to be transferred to the sample in a controllable manner and initiated the reactions. The state of the nanoparticles after the shock wave passage was investigated in detail, focusing on the type and quantities of new surface functional groups and new chemical connections in the bulk samples. It was found that polyethylene predominantly reveals surface hydroxyl groups (some of which can be protonated) and has the ability to release linear polyhydroxy alcohols. Other surface functional groups with significant presence are ether groups. The degradation of polystyrene proceeds through the addition of hydroxyl groups primarily to the benzene rings, causing their dearomatization. The number of hydroxyl groups in a single ring increases with the degree of degradation, and some hydroxyl groups are also protonated. Polystyrene is also susceptible to crosslink formation, mainly between aromatic rings, leading to branched and dearomatized forms that are chemically distinct from styrene. Full article

Background/Objectives: Vascular aging is associated with increased arterial stiffness and changes in the wall structure, leading to a loss of elasticity. Silicon is abundant in arteries and plays a key role in the synthesis and stabilization of elastin fibers. In animal models of accelerated cardiovascular aging, a specific nutritional supplement based on silicon-enriched spirulina (SpSi) has been shown to have beneficial effects on vascular function. The present study, designed as a randomized, double-blind, placebo-controlled trial, aimed to evaluate the effectiveness of this SpSi supplement on aging-related changes in vascular function among healthy older adults. Methods: Here, 120 healthy volunteers aged 60–75 years were enrolled and randomly assigned to either the SpSi group (n = 60) or placebo group (n = 60). Over 6 months, the participants received either 3.5 g of specific 1% silicon-enriched spirulina (SpSi group) or placebo tablets daily. The primary outcome was the assessment of arterial wall pressure waveforms, which included blood pressure (BP) readings and the determination of the aortic pulse wave velocity (aPWV). Secondary outcomes included the vasomotor endothelial function through post-ischemic vasorelaxation, measured using the reactive hyperemia index (RHI), and carotid intima–media thickness. Results: When considering the entire sample, none of the studied parameters differed between the placebo and SpSi groups. However, when focusing on individuals with high–normal blood pressure (i.e., systolic BP between 130 and 150 mmHg) and aPWV levels above cutoff values (>10 m/s), the BP decreased by 8% (p < 0.001) and aPWV decreased by 13.5% (p < 0.0001) in subjects receiving SpSi. In individuals with BP and aPWV levels below the cutoff values, no effect was observed. Conclusions: In healthy elderly individuals, SpSi supplementation improved high–normal blood pressure and aortic pulse wave velocity, suggesting an enhanced vascular function. Full article

Enhancing rural teacher agency to foster more proactive and enthusiastic teaching practices is crucial for addressing the underdeveloped state of rural education. In recent years, the introduction of performance-based personnel management, such as performance-based pay, has been a significant reform initiative. This study focuses on the first county in Beijing to implement performance-based personnel management, conducting a three-year longitudinal investigation to explore how established Western management policies perform when confronted with guanxi (Chinese-style relationships) that emphasize familiarity and personal ties. Using Hierarchical Linear Modeling, the study analyzes three waves of longitudinal data from 516 teachers in a Beijing county, examining the impact of performance-based personnel management on teacher agency and the mediating and moderating roles of guanxi. The findings reveal that (1) Performance-based personnel management did not enhance teacher agency as anticipated. In fact, the stronger the initial guanxi among teacher groups, the more negative the policy’s impact on teacher agency. (2) Guanxi culture exerted a suppressing effect on the policy. In rural China, the indigenous guanxi culture hindered the implementation of performance-based personnel management, eroding collaborative networks among teachers and obscuring the policy’s intended positive effects. Performance-based personnel management weakened work connections among strong-guanxi groups while directly boosting the agency of weak-guanxi groups. (3) Instrumental guanxi demonstrated greater adaptability to policy changes compared to affective guanxi. Overall, externally imposed performance-based personnel management faces significant adaptive challenges within China’s deeply rooted guanxi culture. The effectiveness of such policies is constrained by their degree of alignment with local cultural and social structures. Therefore, policymakers should consider local cultural characteristics in educational policy design to enhance the adaptability and effectiveness of these policies. Full article

Semisubmersible floating structures are becoming the predominant understructure type for floating offshore wind turbines (FOWTs) worldwide. As FOWTs are erected far away from land and in deep seas, they inevitably suffer violent and complicated sea conditions, including extreme waves and winds. Mooring lines are the representative flexible members of the whole structure and are likely to incur damage due to years of impact, corrosion, or fatigue. To improve mooring redundancy at each azimuth angle around a wind turbine, a group of mooring lines are configured in the same direction instead of just one mooring line. This study focuses on the mooring failure problems that would probably occur in a realistic redundant mooring system of a semisubmersible FOWT, and the worst residual mooring layout is considered. An FOWT numerical model with a 3 × 3 mooring system is established in terms of 3D potential flow and BEM (blade element momentum) theories, and aero-hydro floating-body mooring coupled analyses are performed to discuss the subsequent time histories of dynamic responses after different types of mooring failure. As under extreme failure conditions, the final horizontal offsets of the structure and the layout of the residual mooring system are evaluated under still water, design, and extreme environmental conditions. The results show that the transient tension in up-wave mooring lines can reach more than 12,000 kN under extreme environmental conditions, inducing further failure of the whole chain group. Then, a deflection angle of 60° may occur on the residual laid chain, which may bring about dangerous anchor dragging. Full article

Climate change impacts are unpredictable and can change rapidly or over time; anthropogenic stressors work synergistically to strengthen their impact on vulnerable ecosystems including in the fisheries sector. This study focused on understanding and documenting the historical occurrence of extreme climate change impacts as exemplified by super typhoon Pablo (Bopha), which wreaked havoc in Baganga, Davao Oriental, almost a decade ago. A mixed-methods approach was used, using semi-structured interviews (N = 120) and focus group discussions (FGD) with small-scale fishers in the four fishing villages to assess the impacts of climate change and their adaptation after the events occurred. Our findings indicate that the fishing villages were exposed to the same impacts of climate change or the super typhoon which destroyed their lives and livelihoods. Consequently, this affected their catch per trip and fishing operations. Moreover, due to the impact of the super typhoon, fishers in Baganga developed psychological distress and trauma (emotional 44% and physical 24%) due to the extreme event. To survive, their adaptation strategies relied on government and non-government assistance provisions and projects, e.g., planting mangrove trees, construction of a seawall with wave breakers, cash-for-work activities, and tourism, as an alternative livelihood. Moreover, our study revealed that the communities have limited knowledge about the impacts of climate change, the local government lacks clear management goals for fisheries conservation and there was widespread use of illegal fishing gear. There is a strong need to implement rules, policies, and adaptation measures to build more resilient fishing communities. Full article

Objectives: Chronic diseases are a significant public health issue, especially for socioeconomically vulnerable population groups. The purpose of this study is to compare the prevalence of chronic diseases in people receiving and not receiving BLS and to determine the prevalence of chronic diseases according to the physical activity and dietary habits of people receiving BLS. Methods: Data were derived from the sixth to ninth waves (2014–2022) of the Korea National Health and Nutrition Examination Survey (KNHANES), focusing on 15,041 participants aged 65 and older. Demographic characteristics, dietary intake, physical activity, and chronic disease status were assessed. Multivariate logistic regression analysis was used to calculate odds ratios for chronic diseases according to physical activity and dietary habits. Results: The BLS group exhibited higher prevalence rates of hypertension and diabetes, along with lower dietary intake of energy, protein, fat, carbohydrates, dietary fiber, and vitamin C, compared to the non-BLS group. A below-average intake of energy and carbohydrates was associated with increased odds of hypertension and diabetes, particularly in the BLS group. For dietary fiber, a significant association with diabetes was found only in the BLS group. Sedentary behavior exceeding 9 h per day was linked to higher odds of chronic diseases in both groups, with stronger associations in the BLS group. Limited walking frequency (less than 1 day per week) further exacerbated risks. Conclusions: BLS recipients demonstrated higher chronic disease prevalence, poorer dietary habits, and more sedentary behavior compared to non-recipients. The associations between lifestyle factors and chronic diseases were generally more substantial in the BLS group, suggesting the need for targeted interventions to improve dietary quality and physical activity patterns in this vulnerable population. Full article