Search Results (12,072)

To address the low trajectory tracking accuracy and limited robustness of conventional reinforcement learning algorithms under complex marine environments involving wind, wave, and current disturbances, this study proposes a proximal policy optimization (PPO) algorithm incorporating an intrinsic curiosity mechanism to solve the unmanned surface vehicle (USV) trajectory tracking control problem. The proposed approach is developed on the basis of a three-degree-of-freedom (3-DOF) USV model and formulated within a Markov decision process (MDP) framework, where a multidimensional state space and a continuous action space are defined, and a multi-objective composite reward function is designed. By incorporating a pure pursuit guidance algorithm, the complexity of engineering implementation is reduced. Furthermore, an improved PPO algorithm integrated with an intrinsic curiosity mechanism is adopted as the trajectory tracking controller, in which the exploration incentives provided by the intrinsic curiosity module (ICM) guide the agent to explore the state space efficiently and converge rapidly to an optimal control policy. The final experimental results indicate that, compared with the conventional PPO algorithm, the improved PPO–ICM controller achieves a reduction of 54.2% in average lateral error and 47.1% in average heading error under simple trajectory conditions. Under the complex trajectory condition, the average lateral error and average heading error are reduced by 91.8% and 41.9%, respectively. These results effectively demonstrate that the proposed PPO–ICM algorithm attains high tracking accuracy and strong generalization capability across different trajectory scenarios, and can provide a valuable reference for the application of intelligent control algorithms in the USV domain. Full article

Background and Objectives: A surgical method is rarely very effective and simple to perform. A Lichtenstein Repair (LR) is one such exception. Because of the very high incidence of inguinal hernia, LR has become the global gold standard in inguinal hernia repair—not only due to its relative simplicity and reproducibility but also because it can be performed under local anesthesia. These attributes facilitated its worldwide adoption, including in underdeveloped and resource limited settings. Today, many variations are performed under the common name “Lichtenstein Repair”. The extent to which these modifications influence outcomes—particularly recurrence and chronic pain—remains unclear. Materials and Methods: To evaluate reasons for variation in the LR technique, a literature review of seven major surgery textbooks was performed. In addition, a questionnaire comprising 17 questions addressing the key steps of the LR was sent to 90 surgeons across 19 different hospitals in Austria (6) and Slovenia (13). The questionnaire focused on core principles described by Lichtenstein and later refined by his successors. The overall response rate was 78%. Results: Descriptions of the LR in major hernia textbooks vary substantially, partly due to the evolution of the technique over time and partly because any subaponeurotic anterior-canal mesh repair is often labeled as “Lichtenstein”. Survey responses demonstrated considerable variation and lack of standardization or uniformity in several critical steps of the LR. More than 50% of respondents reported using pre-formed meshes that they excessively trim, limiting adequate coverage of the inguinal region. Furthermore, routine patient follow-up is lacking in the majority of cases. Conclusions: The contemporary umbrella term “Lichtenstein Repair” encompasses many different anterior mesh techniques. While some surgeon-specific preferences may not compromise integrity, strict adherence to the evidence-based key principles of the original repair remains essential to minimize recurrences and chronic inguinal pain. Standardization with meticulous adherence to the key principles of the LR is critical to ensure the data submitted into registries, RCTs, and meta-analyses are accurate, comparable, and meaningful. Full article

The ZN Oilfield shale reservoir is characterized by thin sand–shale interbeds, strong lateral and vertical heterogeneity, poor porosity–permeability, low formation pressure coefficient, and low brittleness, which together limit fracture propagation and suppress production after conventional hydraulic fracturing. To overcome these constraints, we propose an intensive-stage, closely spaced volumetric fracturing technology that couples energy-replenishment pressurization with differentiated parameter design. Numerical simulations were used to quantify how injected fluid volume affects the post-fracturing formation pressure coefficient and estimated ultimate recovery (EUR), and to determine economically optimal energy-replenishment scales. Guided by a “dual sweet spot” evaluation (geological + engineering), field designs reduced stage spacing from 80–100 m to 30–50 m and cluster spacing from 10–20 m to 6–10 m, and increased proppant and fluid intensities to ~5.0 t/m and 22.0 m³/m, respectively. Field monitoring and production data show average fracture half-length increased to 193 m, and average initial oil production per well rose from 8.8 t/d to 12.9 t/d (≈46% increase). These results demonstrate that the proposed approach effectively enlarges fracture-controlled reservoir volume, enhances formation energy, and substantially improves single-well performance in low-pressure shale oil systems. Full article

Background: Social media use has grown rapidly and has been integrated into the lives of many adolescents and young adults worldwide. Research indicates that excessive social media engagement can negatively impact sleep quality through various mechanisms. Objective: This scoping review of reviews aims to explore the relationship between social media use and sleep quality among adolescents and young adults, synthesize existing evidence, identify research gaps, and highlight directions for future research. Methods: Arksey’s and O’Malley’s five-stage framework was used to conduct this scoping review. Searches were conducted in PubMed, Web of Science, Embase, Medline, and Scopus for articles published between 2020 and 2025. The inclusion criteria were systematic reviews or meta-analyses focused on adolescents and young adults, examining social media use in relation to sleep quality, and peer-reviewed articles written in English. Ten articles met all eligibility criteria and were included in the review. Results: The findings indicate a small but consistent negative effect of social media use on sleep quality. Problematic social media use showed a stronger association with poorer sleep than general social media use. Specific platforms such as Facebook and Twitter contributed most to shorter sleep duration, later bedtimes, and poorer sleep quality, while Snapchat and Instagram showed moderate effects, and WhatsApp and WeChat showed smaller effects. Conclusions: Problematic social media use is strongly associated with poorer sleep quality, while general use may have smaller effects. Future research focusing on longitudinal studies would help deepen the understanding of the effects of social media on sleep and guide targeted interventions. Encouraging responsible or healthy social media use is vital in reducing the risks of problematic use while highlighting the benefits as well. Full article

This study established a marine atmospheric corrosion prediction model by comparing the corrosion behavior of 7075 aluminum alloy in neutral salt spray tests and outdoor exposure tests conducted in the coastal atmosphere of Hainan. The results show that severe rusting occurred after 96 h of neutral salt spray testing, with loose white cluster-like corrosion products mainly composed of Al(OH)₃ and Al₂O₃. The thickening of the corrosion product layer slowed down the corrosion process, following a nonlinear power-law kinetic relationship. In the later stage, potential dropped sharply due to product layer spallation, and recovered as new corrosion products formed, confirming that the stability of the product layer is critical for protection. Under coastal atmospheric exposure, the composition of corrosion products was similar to that observed in the salt spray test, but the actual corrosion rate was affected by environmental dynamic equilibrium. The acceleration factor of the neutral salt spray test corresponding to the same corrosion amount in the Hainan marine atmosphere exhibited a declining trend, reflecting that differences in the protective nature of the corrosion product layer were influenced by environmental factors. Electrochemical analysis indicated that both tests showed similar current–potential synergistic variation mechanisms dominated by product layer stability. In summary, while the neutral salt spray test effectively simulates the chloride-induced corrosion mechanism in marine atmospheres, its kinetic model cannot directly predict real corrosion behavior through a simple acceleration factor, as environmental complexity must be considered. Full article

The Axi gold deposit, a low-sulfidation epithermal deposit in the Western Tianshan, China, hosts over 50 t of gold resources and is widely regarded as the result of coupled processes of rock deformation, heat transfer, pore fluid flow, and chemical reactions. However, research on the ore-forming processes of this gold deposit from a coupled perspective remains limited, resulting in its ore-forming mechanisms being incompletely understood. In this paper, we use the concept of mineralization rate based on computational modeling to indicate the 3D spatial distribution of mineralization. The simulation results reveal the following: (1) temperature gradients play a key role in influencing mineral precipitation, whereas the effect of pore fluid pressure gradients is relatively negligible; (2) gold precipitation, characterized by a negative mineralization rate, predominantly took place along fault zones that exhibit vertical transitions from steep to gentle slopes or lateral bends, which are further distinguished by the accumulation of fluids and the presence of significant temperature gradients. Notably, this particular distribution pattern of gold precipitation closely mirrors the spatial arrangement of known gold orebodies. These findings suggest that the coupling of multiple physical and chemical processes at specific fault sites plays a critical role in ore formation, providing new insights into the mechanisms governing the development of the Axi gold deposit. Furthermore, based on these observations, it can be inferred that the deeper regions of the Axi gold deposit hold considerable mineralization potential. Full article

Background and Objectives: The insertion of endosseous implants requires the alveolar bone to be drilled, which produces alterations of the osseous neoalveolus approximately 1 mm deep, an area that will later be subjected to osseous renewal. The healing of the bone around the inserted implant is complex and depends on numerous factors, amongst which the size of the insertion orifice relative to the diameter of the implant, the design, and the pace and depth of the threads play an essential part. Therefore, the aim of this paper is to investigate from a histologic point of view the osseointegration of the implants inserted in a rabbit cortical bone by creating a 150 µm high healing chamber. Materials and Methods: 5 mm-long and 2 mm-wide titan implants were inserted into the femur of 15 12-month-old rabbits by using a drill with a 1.8 mm diameter, obtaining a spiralled healing chamber 150 µm high. The animals were euthanized after 7, 14, and 28 days according to effective legal and ethical protocols. The bone around the implants was severed 5 µm thick. After coloring with the Tricrom Goldner method, the sections that intercepted most centrally the intervention area were examined and photographed with an Olympus microscope. Results: The histologic result showed osseous healing within the healing chamber in the third to the endosteum of the implant after 7 days from the insertion. After 14 days, the osseous healing spread to 2/3 of the healing chamber. After 28 days, the whole healing chamber was occupied by bone. Conclusions: The healing chamber favored proper conditions for osseous healing, which began at the level of the endosteum. This statement is based on the histologic findings of bone formation after 7 days only in the third of the endosteum of the healing chamber. A 150 µm height of the healing chamber obtained in the rabbit cortical bone does not pose a risk of connective tissue proliferation. Full article

The Yellow River Floodplain region of Shandong Province is dominated by silty soils that challenge geotechnical construction. Drilling–Mixing–Jetting (DMJ) Deep Cement Mixing Pile groups have been adopted to improve the geotechnical properties of the soil. This study conducted field tests to evaluate column strength and numerically investigated the effects of area replacement ratio (7.10%, 10.66% and 14.21%) and column spacing. It is observed that the DMJ-integrated columns demonstrate enhanced soil–cement strength in the Yellow River Floodplain region, with sample strengths varying between 2 and 8 MPa. The electrical resistivity of soil–cement shows a strong linear correlation (Pearson’s R > 0.75) with unconfined compressive strength. Settlement reduction ratios range between 32.11% and 94.75% and increase with higher area replacement ratio (ARR) and applied stress but decrease with larger column spacing. Bearing capacity improvement factors are found to be increased with ARR, while column spacing has minimal effect, with values between 423.89 kPa and 431.61 kPa. Lateral displacement decreased with column installation and increasing area replacement ratio (ARR), while the effect of column spacing was confined to depths near the column head. Full article

Background: Chronic pain after unicompartmental knee arthroplasty (UKA) represents a significant clinical issue, often unrelated to mechanical causes and resistant to standard therapies. This work combines a narrative review and a case report to explore the pathophysiological mechanisms underlying persistent post-UKA pain and to propose genicular artery embolization (GAE) with Imipenem/Cilastatin (IPM/CS) as a novel minimally invasive treatment option. Methods: A comprehensive literature review was conducted to analyze current diagnostic and therapeutic approaches to chronic post-UKA pain, with emphasis on vascular and inflammatory mechanisms. Additionally, a patient with chronic lateral knee pain refractory to conservative management underwent selective GAE targeting hypervascularized genicular branches. Results: Following the procedure, the patient experienced substantial and sustained pain reduction, functional improvement, and no complications. The literature supports synovial neovascularization as a potential pain generator and confirms the safety of IPM/CS due to its transient embolic effect and preservation of normal perfusion. Conclusions: The combination of literature review and clinical evidence suggests that GAE may represent a promising therapeutic alternative for chronic post-UKA pain. Further studies are needed to confirm its efficacy, long-term outcomes, and appropriate indications within this challenging clinical setting. Full article

Maintaining the stability of the mine roadway is of paramount importance, as it is critical in ensuring the daily operational continuity, personnel safety, long-term economic viability, and sustainability of the entire mining operation. Significant instability can trigger serious disruptions—such as production stoppages, equipment damage, and severe safety incidents—which ultimately compromise the project’s financial returns and future prospects. Therefore, the proactive assessment and rigorous control of roadway stability constitute a foundational element of successful and sustainable resource extraction. In China, thick and extra-thick coal seams constitute over 44% of the total recoverable coal reserves. Consequently, their safe and efficient extraction is considered vital in guaranteeing energy security and enhancing the efficiency of resource utilization. The surrounding rock of gob-side roadways in typical coal seams is often fractured due to high ground stress, intensive mining disturbances, and overhanging goaf roofs. Consequently, asymmetric failure patterns such as bolt failure, steel belt tearing, anchor cable fracture, and shoulder corner convergence are common in these entries, which pose a serious threat to mine safety and sustainable mining operations. This deformation and failure process is associated with several parameters, including the coal seam thickness, mining technology, and surrounding rock properties, and can lead to engineering hazards such as roof subsidence, rib spalling, and floor heave. This study proposes countermeasures against asymmetric deformation affecting gob-side entries under intensive mining pressure during the fully mechanized caving of extra-thick coal seams. This research selects the 8110 working face of a representative coal mine as the case study. Through integrated field investigation and engineering analysis, the principal factors governing entry stability are identified, and effective control strategies are subsequently proposed. An elastic foundation beam model is developed, and the corresponding deflection differential equation is formulated. The deflection and stress distributions of the immediate roof beam are thereby determined. A systematic analysis of the asymmetric deformation mechanism and its principal influencing factors is conducted using the control variable method. A support approach employing a mechanical constant-resistance single prop (MCRSP) has been developed and validated through practical application. The findings demonstrate that the frequently observed asymmetric deformation in gob-side entries is primarily induced by the combined effect of the working face’s front abutment pressure and the lateral pressure originating from the neighboring goaf area. It is found that parameters including the immediate roof thickness, roadway span, and its peak stress have a significant influence on entry convergence. Under both primary and secondary mining conditions, the maximum subsidence shows an inverse relationship with the immediate roof thickness, while exhibiting a positive correlation with both the roadway span and the peak stress. Based on the theoretical analysis, an advanced support scheme, which centers on the application of an MCRSP, is designed. Field monitoring data confirm that the peak roof subsidence and two-side closure are successfully limited to 663 mm and 428 mm, respectively. This support method leads to a notable reduction in roof separation and surrounding rock deformation, thereby establishing a theoretical and technical foundation for the green and safe mining of deep extra-thick coal seams. Full article

In order to effectively reveal the nonlinear characteristics of a dish concentrating solar thermal power system (DCSTPS) under pulsating wind-induced loads, a fluid simulation model of the DCSTPS was established, and the simulated pulsating winds were developed via the user-defined function (UDF) combined with the autoregressive (AR) model using MATLAB (R2015b). And based on the fluid simulation calculations of the DCSTPS, the time-range data of the relevant wind vibration coefficients under different working conditions were obtained. The research results show the following: (1) When the altitude angle α is 0° or 180° due to the azimuth angle β = 0°, the maximum values of their drag coefficient C_x, lateral force coefficient C_y, and lift coefficient C_z are similar, and the maximum of rolling moment coefficient C_Mx is significantly smaller than the values at the other two angles; the maximum of the pitch moment coefficient C_My and maximum of the azimuth moment coefficient C_Mz are significantly larger than the values of the other two angles. (2) The increase in altitude angle α leads to a reduction in the drag coefficient C_x, an increase in the lift force coefficient C_z, and an increase of the pitch moment C_Mx. Moreover, an improved phase space delay reconstruction method was developed to calculate the delay time, Lyapunov exponent, and Kolmogorov entropy of the DCSTPS, and the research results show that (1) the maximum Lyapunov exponent and Kolmogorov entropy of the DCSTPS are greater than zero under the action of pulsating wind; (2) the action of pulsating wind will cause increases in the maximum Lyapunov exponent and Kolmogorov entropy of the DCSTPS and will accelerate the divergence speed of the DCSTPS trajectory; and (3) the time for the DCSTPS to enter the chaotic state will be shortened, while the time of entering a chaotic state and degree of subsequent chaotic states will be significantly affected by relevant wind vibration coefficients but without regularity. Full article

The construction and facilities management sectors are increasingly adopting automation technologies to improve productivity and reduce manual labor. In parallel, decorative and informational floor-marking is widely used in indoor environments such as schools, exhibition halls, and public spaces to support organization, wayfinding, and visual communication. While robotic systems have been developed for floor and layout marking, many existing solutions rely on specialized infrastructure or offer limited flexibility in the range of patterns that can be produced. This paper presents the development of a prototype of a mobile, wheeled robot capable of autonomously executing diverse designs on surfaces such as fields and floors. The robot’s potential applications include use on indoor floors and exhibition halls. It marks the ground using a plotting pen while navigating and avoiding obstacles within its environment. Additionally, the robot can produce a range of drawings, including letters and signage, and its capabilities can be extended to create decorative patterns as well as marks for floor-based games. This robot was constructed entirely from cost-effective, commercially available components. Experimental evaluation demonstrates repeatable motion and drawing performance, with measured standard deviations of approximately 1.6 mm in forward motion and 3 mm in lateral motion during representative grid-based traversal. These results indicate that the proposed approach achieves a level of accuracy and consistency sufficient for decorative floor-marking and similar applications, without reliance on external localization infrastructure. Full article

The App Store introduced a title-length limit for mobile apps in 2016, and similar policies were later adopted across the industry. This issue drew considerable attention from industry practitioners in the 2010s. Using both empirical and theoretical approaches, this paper examines the effectiveness of this policy and its welfare implications. Title length became an issue because some sellers assemble meaningful keywords in the app title to convey information to consumers, while others combine irrelevant yet popular keywords in an attempt to increase their app’s downloads. We hypothesize that when titles are short, title length is positively associated with an app’s performance because both honest and opportunistic sellers coexist in the market. However, due to the presence of opportunistic sellers, once titles become too long, this positive relationship disappears. We examine this hypothesis using a random sample of 1998 apps from the App Store in 2015. Our results show that for apps with titles longer than 30 characters, title length remains positively associated with app performance. However, for titles exceeding 50 characters, we do not have sufficient evidence to conclude that further increases in length continue to generate additional downloads. To interpret our empirical findings, we construct communication games between an app seller and a consumer, in which the equilibrium is characterized by a threshold. Based on our model and empirical observations, the 30-character limit might hurt consumers. Full article

Cardiac myosin inhibitors have been shown to improve diastolic function in patients with obstructive hypertrophic cardiomyopathy (HCM). Comparative studies to evaluate the diastolic effects of mavacamten versus alcohol septal ablation (ASA) have yet to be examined. In this single-center retrospective analysis, we compared echocardiographic parameters of diastolic function in adult patients with obstructive HCM treated with mavacamten (n = 23) or ASA (n = 22). Baseline imaging was obtained prior to therapy, and follow-up imaging was obtained five months after ASA and or initiation of mavacamten. Left-sided filling pressures (E/e’) improved with both ASA (18.6 versus 15.3, p < 0.001) and mavacamten (17.4 versus 13.5, p = 0.01). Among patients who underwent ASA, mitral annular tissue velocity (e’) was increased at the lateral annulus (6.0 versus 6.1, p = 0.02) with a trend to improvement at the septum (4.0 versus 5.0, p = 0.14). Similarly, among patients treated with mavacamten, septal e’ was increased (6.0 versus 6.7, p < 0.01) and a trended improvement was observed for the lateral e’ (5.7 versus 7.0, p = 0.06). Mavacamten therapy was also associated with an improvement in the LA volume index (45.6 versus 34.5, p < 0.001). Patients treated with ASA were older, more likely to have used tobacco, and had greater limitation in functional status. In this retrospective analysis, ASA and mavacamten were similarly associated with improvements in echocardiographic parameters of diastolic function and left-sided filling pressures, though mavacamten had a more discernible effect on the left-atrial volume index. Larger studies are required to further characterize the relative efficacy of the two therapeutic modalities. Full article

Background: Status epilepticus (SE) is a neurological emergency with high morbidity and mortality in childhood, where rapid and effective intervention is essential to prevent neuronal injury. Experimental studies suggest that time-dependent loss of GABAergic responsiveness creates an early therapeutic window during which benzodiazepines are most effective for acute seizure suppression. Methods: This retrospective study analyzed 63 pediatric patients (mean age 46.5 ± 4.9 months) with first-episode SE treated between 2008 and 2022. Patients were categorized according to the timing of continuous midazolam infusion as early (≤15 min from seizure onset) or late (>15 min). Primary outcome was time to seizure control; secondary outcomes included infusion duration and epilepsy development during two-year follow-up. Results: Early infusion significantly shortened time to seizure control (21.8 ± 1.5 min vs. 29.3 ± 2.8 min, p = 0.029) and reduced infusion duration (18.4 ± 2.5 h vs. 32.7 ± 7.5 h, p = 0.049) compared with later initiation. Epilepsy developed in 74.6% of patients over two years, with no significant difference between early and late infusion groups (p = 0.079). Conclusions: Initiating continuous midazolam infusion within 15 min of seizure onset defines a clinically relevant early therapeutic window for pediatric SE. While infusion timing did not significantly alter long-term epileptogenesis, early initiation was associated with improved acute seizure control and shorter treatment duration, underscoring the importance of time-sensitive intervention in pediatric neuroemergencies. Full article