Search Results (1,087)

All grid faults can cause significant problems within the power grid, including disconnection or malfunctions of wind energy conversion systems (WECSs) connected to the power grid. This study proposes a comparative analysis of the fault ride-through capability of a WECS-based permanent magnet synchronous generator (PMSG) system. To overcome these issues, active crowbar and capacitive bridge fault current limiter-based machine learning algorithm protection methods are implemented within the WECS system, both separately and in a hybrid. The regression approach is applied for the machine-side converter (MSC) and the grid side converter (GSC) controllers, which involve numerical data. The classification method is employed for protection system controllers, which work with data in distinct classes. These approaches are trained on historical data to predict the optimal control characteristics of the wind turbine system in real time, taking into account both fault and normal operating conditions. The neural network trilayered model has the lowest root mean squared error and mean squared error values, and it has the highest R-squared values. Therefore, the neural network trilayered model can accurately model the nonlinear relationships between its variables and demonstrates the best performance. The neural network trilayered model is selected for the MSC control system in this study. On the other hand, support vector machine regression is selected for the GSC controller due to its superior results. The simulation results demonstrate that the proposed machine learning algorithm performance for WECS based on a PMSG is robustly utilized under different operating conditions during all grid faults. Full article

The aim of this research is to present both a sensorless control and a torque derating algorithm in the overload region of a permanent magnet motor for e-bikes. First, the theoretical backgrounds and the field-oriented control are presented. Then, a sensorless control is designed based on the back-emf estimation with a second-order generalized integral flux observer for the permanent magnet motor. The second-order generalized integral flux observer is an adaptive filter which can eliminate the DC offset and strongly attenuate the harmonics of the estimated rotor flux. The algorithms have been simulated and then validated by means of tests on a permanent magnet motor for e-bikes. Full article

We present a novel concept of an electromagnetic mechanism for shifting the centre of gravity (CoG) in a small unmanned aerial vehicle with four rotors (quadrotor). Shifting the CoG is essential for controlling drones in which the thrust is unbalanced (e.g., upon the failure of one of the drives). The concept presented here involves using electromagnetic coils mounted under the drone and moving permanent magnets inside a cylindrical tube. Moving the positions of the masses can be controlled by means of currents in the coils. Changing the position of the magnets relative to the arms of the drone causes a shift in the CoG, allowing for controllability even when one of the four engines is not working, and making it possible for the drone to land safely. This article describes the geometrical and mechanical relationships in the proposed system, the design and numerical calculations of the electromagnetic mechanism with coils and permanent magnets, as well as the results of a simulation of the control variant. Additionally, the practical implementation of the mechanism, from CAD modelling through the manufacturing of its elements to the final structure prepared for mounting on a quadrotor, is discussed. Full article

Objective: In this study, we aimed to determine the most significant risk factors for 5-year mortality in patients with paroxysmal and persistent drug-refractory tachysystolic atrial fibrillation after undergoing atrioventricular node ablation (AVNA) in combination with the implantation of a permanent three-chamber pacemaker with an implantable cardioverter–defibrillator function (CRT-D). Methods: This prospective single-center cohort study included 101 patients with chronic heart failure (mean age 62 ± 15.5 years; 70.3% male) with paroxysmal or persistent drug-refractory atrial fibrillation who underwent atrioventricular node ablation and CRT-D implantation. All patients received optimal medical therapy before and after undergoing the procedure. Predictors of 5-year mortality were assessed using exploratory machine-learning methods, including random forest and Shapley additive explanations. Results: During 5-year follow-up, 13 cardiovascular deaths were recorded. Five key predictors of mortality were identified: left ventricular ejection fraction, 6 min walk distance, mean pulmonary artery pressure, systolic relaxation coefficient, and degree of mitral regurgitation. The exploratory predictive model showed high accuracy (92%) in terms of classifying the outcomes. Conclusions: Atrioventricular node ablation (AVNA) combined with CRT-D was associated with the observed long-term clinical outcomes observed in patients with drug-refractory tachysystolic atrial fibrillation. The exploratory machine learning analysis identified key mortality-associated factors, which may support future efforts in personalized risk stratification and hypothesis generation. The combination of AVNA and CRT-D was associated with the observed long-term outcomes in this real-world cohort. Full article

This study presents SpineCheck, a fully integrated deep-learning-based clinical decision support platform for automatic vertebra segmentation and Cobb angle (CA) measurement from scoliosis X-ray images. The system unifies end-to-end preprocessing, U-Net-based segmentation, geometry-driven angle computation, and a web-based clinical interface within a single deployable architecture. For secure clinical use, SpineCheck adopts a stateless “process-and-delete” design, ensuring that no radiographic data or Protected Health Information (PHI) are permanently stored. Five U-Net family models (U-Net, optimized U-Net-2, Attention U-Net, nnU-Net, and UNet3++) are systematically evaluated under identical conditions using Dice similarity, inference speed, GPU memory usage, and deployment stability, enabling deployment-oriented model selection. A robust CA estimation pipeline is developed by combining minimum-area rectangle analysis with Theil–Sen regression and spline-based anatomical modeling to suppress outliers and improve numerical stability. The system is validated on a large-scale dataset of 20,000 scoliosis X-ray images, demonstrating strong agreement with expert measurements based on Mean Absolute Error, Pearson correlation, and Intraclass Correlation Coefficient metrics. These findings confirm the reliability and clinical robustness of SpineCheck. By integrating large-scale validation, robust geometric modeling, secure stateless processing, and real-time deployment capabilities, SpineCheck provides a scalable and clinically reliable framework for automated scoliosis assessment. Full article

Spatial heterogeneity of species distributions modulates local interactions and dynamics, playing a key role in the development of diversity and ecosystem functioning during secondary succession. Here, we tested the cycling heterogeneity hypothesis, which predicts fluctuating spatial beta diversity, i.e., alternating periods of high and low heterogeneity during succession, driven by the changes in the abundance of dominant species. We analyzed long-term monitoring data collected annually along 52 m long permanent transects over 15 years in abandoned fields. Recovery of grassland vegetation was fast due to the humus-rich chernozem soil, the rich species pool, and the fast colonization of native grassland species from adjacent natural meadow steppe. Heterogeneity was quantified by spatial beta diversity as the mean pairwise dissimilarity among sampling units. Incidence-based (Jaccard) and abundance-based (Bray–Curtis) indices were used. We found large temporal fluctuations in spatial heterogeneity, with amplitudes reaching 80–100% of the total beta diversity range across the successional gradient. Two major beta diversity peaks were identified: maximum heterogeneity occurred during transitions between successional phases, whereas periods of minimum heterogeneity coincided with the sequential dominance of a few particular species. Bromus sterilis and Festuca valesiaca were the most important species driving heterogeneity. Similar patterns were recorded at two monitoring sites. Changing the sampling unit size computationally, varying the dissimilarity indices, or excluding dominant species had little influence on the results. Using null models, we removed the effects of species richness and abundance and found an increasing degree of spatial dependence as succession progressed. However, the corresponding beta deviations also showed non-linear, fluctuating patterns. Our results support the cycling heterogeneity hypothesis in secondary grassland succession. Increasing understanding of heterogeneity patterns provides new opportunities to optimize the temporal and spatial design of grassland restoration measures. Full article

Background/Objectives: Vogt–Koyanagi–Harada (VKH) disease is a bilateral granulomatous panuveitis that can progress to a chronic, relapsing phase. Patients refractory or intolerant to systemic corticosteroids and conventional immunomodulatory therapy pose a major therapeutic challenge, as persistent inflammation can lead to cumulative ocular damage and permanent vision loss. This study assessed the efficacy of tumor necrosis factor-α (TNF-α) inhibitor adalimumab in chronic recurrent VKH disease. Methods: We retrospectively reviewed 16 eyes from 8 patients with chronic recurrent VKH disease who had persistent inflammation despite treatment with corticosteroids and conventional immunomodulatory therapy, and subsequently received adalimumab. Primary outcomes were changes in subfoveal choroidal thickness (SFCT) and systemic corticosteroid dose reduction. Secondary outcomes included visual acuity, inflammatory parameters (anterior chamber cell, flare, and vitreous haze), and central macular thickness (CMT). All outcomes were compared between baseline and 6 months after adalimumab initiation using the Wilcoxon signed-rank test. Results: Mean patient age was 47.6 years and mean follow-up was 31.8 months. SFCT decreased from 326.7 ± 129.1 µm to 231.6 ± 72.9 µm at 6 months (p < 0.001). Systemic steroid dose decreased from 14.7 ± 14.0 mg to 4.1 ± 3.8 mg (p = 0.027). Mean annualized relapse rate decreased from 3.61 to 0.08 episodes/year (p = 0.012). Anterior chamber cell grade decreased from 0.81 ± 0.66 to 0.09 ± 0.20 (p < 0.001). Visual acuity, flare, vitreous haze, and CMT showed no significant change. No serious adverse events occurred. Conclusions: TNF-α inhibition with adalimumab appears effective as steroid-sparing therapy for controlling recurrent inflammation and reducing steroid dependence in patients with chronic recurrent VKH disease refractory to conventional treatment. Full article

Background: Atrial high-rate episodes (AHREs) detected by pacemakers are linked to increased stroke risk. The predictive value of high-sensitivity cardiac troponin I (hs-cTnI) for AHREs in pacemaker patients remains uncertain. This study evaluated baseline hs-cTnI as a predictor for new-onset AHREs in this population. Methods: This prospective cohort study enrolled 272 patients undergoing permanent pacemaker implantation. We excluded 40 patients with pre-existing atrial fibrillation (AF), leaving a total of 232 patients (mean age 63.7 years; 53.4% male) in the at-risk cohort. Baseline hs-cTnI and NT-proBNP were measured. The primary endpoint was new-onset AHREs (>175 bpm), detected by device interrogation over a median follow-up of 12 months. Results: New-onset AHREs occurred in 65 (28.0%) patients. Contrary to our hypothesis, baseline hs-cTnI levels did not differ significantly between patients who developed AHREs and those who did not (median 16.5 vs. 15.7 pg/mL, p = 0.148). Multivariable Cox regression confirmed that neither hs-cTnI nor NT-proBNP were independent predictors. Instead, Sick Sinus Syndrome (HR 2.10, p < 0.001), heart failure (HR 1.78, p = 0.010), and Left Atrial Diameter (HR 1.15, p = 0.006) were significant independent predictors. Conclusions: In this high-risk pacemaker cohort, baseline hs-cTnI and NT-proBNP did not predict short-term new-onset AHREs. Established electrical and structural substrates appear to be the overwhelming drivers of arrhythmia in this specific population. Full article

Background: Dental caries is currently the most common chronic disease affecting the Spanish pediatric population. Therefore, the main objective of this study was to assess Caries Management by Risk Assessment (CAMBRA) in children attending a university dental clinic between the ages of 6 and 12 and establish the DMFT (decayed, missing, and filled teeth index for permanent teeth) of the sample. In addition, the study calculated the plaque index, salivary pH level, buffering capacity, and the quantity and quality of saliva in the sample and determined if there were statistical differences between sexes and between subgroups with DMFT = 0 (control) and DMFT > 0 (cases). Methods: A case–control study was conducted with 89 patients aged 6 to 12 years. Clinical and salivary indicators were measured. Caries risk was also assessed using the CAMBRA protocol, and the sample was also divided into control and case groups for further analysis. Results: The CAMBRA questionnaire showed that 65.2% of participants presented a high risk of caries. The sample showed an average DMFT of 0.65 with a plaque index of 57.2%. The mean salivary pH was 7.35 (±0.30). The average volume of stimulated saliva was 6.83 mL (±3.68), and the buffering capacity was classified as normal in 57% of cases. No statistically significant differences were found between sexes or in the evaluated risk factors. In the control group, the mean salivary pH value was 7.35, and the amount of stimulated saliva was 6.5 mL. The buffering capacity was classified as normal in 67% of cases. In contrast, the case group presented a mean pH value of 7.15 and a salivary volume of 5 mL, with a normal buffer capacity in 50% of cases. Conclusions: The CAMBRA protocol indicated that more than half of the participants presented a high risk of caries, indicating the need to customize treatment plans for each patient. The salivary pH showed statistic differences between the control and case groups, indicating the importance of incorporating salivary biomarkers into routine clinical practice. Full article

Background/Objectives: The aim of this study was to evaluate the accuracy of aesthetic assessments performed by artificial intelligence (AI)-based large language models (LLMs) using the Aesthetic Component of the Index of Orthodontic Treatment Need (IOTN-AC), which is widely applied to determine the need for orthodontic treatment. Methods: A total of 150 frontal intraoral photographs from patients in the permanent dentition, scored from 1 to 10 on the IOTN-AC, were assessed by two AI-based LLMs (ChatGPT-5 and ChatGPT-5 Pro). Two experienced clinicians independently scored all photographs, with one evaluator’s scores used as the reference (κ = 0.91, ICC = 0.88). Model performance was analyzed by comparing IOTN-AC scores and treatment need classifications. In addition, performance parameters such as accuracy, precision, specificity, and sensitivity were evaluated. Statistical analyses included Spearman correlation, Cohen’s Kappa, ICC, Mean Absolute Error (MAE), Wilcoxon signed-rank test, and Bland–Altman analysis. Results: Both models demonstrated positive and significant correlations with the reference values for scoring and classification (p < 0.001). Compared to GPT-5 Pro, the GPT-5 model exhibited superior performance, with a lower error rate (MAE = 1.47) and higher classification accuracy (66.7%). Bland–Altman analysis showed that most predictions fell within the 99% confidence interval, and regression analysis revealed no systematic bias (p > 0.05). Conversely, the models failed to achieve consistently high performance in each of the performance parameters. Conclusions: The findings revealed that although AI-based LLMs are promising, statistical accuracy alone is insufficient for safe clinical use, and they should demonstrate consistently high performance across all parameters. Full article

Aim: This ex vivo study aimed to evaluate the effect of low-energy 445 nm diode laser irradiation on permanent fluoride retention in human enamel. Materials and Methods: Eighty caries-free extracted permanent human teeth were used to prepare 480 enamel discs (2 × 2 mm). Baseline fluoride content in untreated enamel specimens (control group E) was measured using particle-induced gamma-ray emission (PIGE). All specimens then received a topical application of acidulated phosphate fluoride for 5 min, followed by rinsing with double-distilled water for 1 min. Fluoride quantification was subsequently repeated. Specimens were randomly allocated into two groups: fluoridated only (EF; n = 240) and fluoridated plus laser-treated (EFL; n = 240). Each group was further subdivided based on storage conditions: either in air or in double-distilled water at 36 °C for 7 days. Laser irradiation was performed using a 445 nm diode laser in continuous-wave mode at 350 mW for 30 s, with a beam diameter of 10 mm, an energy density of 13.375 J/cm², and a power density of 0.445 W/cm². Results: At baseline, mean fluoride content across all specimens was 702.23 ± 201 ppm. Immediately after fluoridation, fluoride levels increased to 11,059 ± 386 ppm in the EF group and 10,842 ± 234 ppm in the EFL group, with no significant difference between groups. After 7 days of storage in air, fluoride retention decreased to 5714 ± 1162 ppm in EF and 5973 ± 861 ppm in EFL, again without significant difference. However, after 7 days of immersion in double-distilled water, the EF group exhibited complete loss of acquired fluoride, with values falling below baseline (337 ± 150 ppm). In contrast, the EFL group retained a substantial portion of the fluoride acquired during fluoridation (total 1533 ± 163 ppm), indicating that laser irradiation significantly prevented fluoride loss (p < 0.001). Conclusions: Low-energy 445 nm diode laser irradiation of fluoridated enamel significantly enhances fluoride retention under aqueous conditions simulating osmotic processes. Laser treatment preserved a substantial portion of fluoride acquired during fluoridation, whereas fluoridated but unlased enamel lost nearly all fluoride, with levels dropping below baseline. This approach may offer clinical benefits for improving enamel fluoride enrichment, thereby increasing resistance to acid challenge and reducing caries risk. Full article

Background: Tooth autotransplantation represents a biologically favourable treatment option for replacing missing or non-restorable teeth in paediatric patients. However, its long-term prognosis and variability in reported success rates warrant a high-quality synthesis of the available evidence. Methods: A systematic review was conducted following the PRISMA 2020 guidelines. A comprehensive search of PubMed, Scopus, Web of Science, and Cochrane CENTRAL was performed up to May 2024 for clinical studies on autotransplantation of immature permanent teeth in patients under 18 years. Study selection, data extraction, and risk-of-bias assessment (using ROBINS-I and JBI tools) were performed independently by two reviewers. Aggregated success and survival proportions with 95% confidence intervals were calculated through descriptive quantitative synthesis. Results: Three retrospective studies, comprising 404 transplanted teeth, were included in the analysis. The aggregated success proportion was 85.4% (95% CI: 74.4–92.1%), and the aggregated survival proportion was 94.2% (95% CI: 85.0–97.9%), with a mean follow-up ranging from 12 to 168 months. A key finding was that all included studies consistently reported the use of immature donor teeth (¹/₂–³/₄ root formation) and short-term flexible splinting, which appears to be a critical factor for these successful outcomes. Conclusions: Autotransplantation of developing teeth in paediatric patients demonstrates high survival (≈94%) and favourable success (≈85%), with minimal inter-study variability. When performed with immature donor roots and short-term flexible splinting, the procedure provides a predictable biological alternative to prosthetic or implant rehabilitation in growing individuals. However, the limited number of eligible studies highlights the need for future multicentre prospective research to standardise protocols and confirm long-term outcomes in paediatric populations. Full article

Background/Objectives: Complex aneurysms of the posterior inferior cerebellar artery (PICA) remain challenging because of their deep location, variable morphology, and proximity to critical neurovascular structures. Although endovascular therapy is preferred, its feasibility is limited in wide-necked, fusiform, or dissecting lesions. We describe our tertiary referral hospital single-center experience with tailored microsurgical and endovascular strategies—emphasizing occipital artery–PICA (OA-PICA) bypass, transcondylar fossa craniotomy, and cerebellomedullary fissure opening—and analyze perioperative factors that influence outcome. Methods: All consecutive patients treated for PICA origin or distal-PICA aneurysms between January 2021 and April 2025 were retrospectively reviewed. Demographics, aneurysm characteristics, procedure type, antithrombotic regimen, complications, diffusion-weighted MRI findings, and 3-month modified Rankin Scale scores were collected. Results: Twelve aneurysms (mean age 61.4 ± 15.2 years; 8 women) were treated: trapping + OA-PICA bypass in 5, direct clipping in 2, flow diverter in 1, endovascular parent artery occlusion in 2, coil embolization in 1, and a hybrid bypass-plus-coil strategy in 1. Two cases were ruptured aneurysms. Perioperative aspirin was used in 2/5 bypass cases; heparin was added in one hybrid case. Asymptomatic PICA-territory infarcts occurred in the three bypasses performed without antiplatelet therapy (one with intra-anastomotic thrombus). No leaks or subcutaneous collections of cerebrospinal fluid were encountered, and no graft occlusions were observed. At 3 months, 9/12 patients achieved a good outcome (mRS 0–2); among them, only one patient with subarachnoid hemorrhage (SAH) experienced postoperative worsening of the mRS. Two cranial nerve palsies (one permanent, one transient) and one wound site hematoma (heparin-associated) resolved without sequelae. Conclusions: Meticulous operative planning allows safe treatment of complex PICA aneurysms. Perioperative aspirin appears beneficial for OA-PICA bypass, whereas perioperative heparin increases bleeding risk. Individualized selection of endovascular, microsurgical, or combined strategies yields favorable early neurological outcomes in this demanding subset of cerebrovascular disease. Full article

Dogs are often viewed as family members, and many owners describe them as “fur babies.” However, little is known about how women with and without children perceive and practice caregiving toward their dogs, and how these experiences relate to parenting. This qualitative study explored the meanings of dog and child caregiving among 28 dog-owning women (13 mothers and 15 childless) through semi-structured interviews. All participants had lived with their dog for at least one year. Thematic analysis identified five main themes: (1) emotional meanings and motivations of caregiving, (2) practical caregiving and daily routines, (3) responsibility and dependency, (4) social relationships and support, and (5) life course perspectives. Both mothers and non-mothers described their dogs as sources of joy, companionship, and unconditional love. Women without children often saw their dogs as child substitutes, while mothers stressed the greater responsibility and permanence of raising children. Dog ownership and parenting influenced social life and work differently: dogs often increased social interaction and offered flexibility, whereas children introduced stricter routines and reduced spontaneity. Overall, dogs fulfilled important emotional and caregiving needs, particularly among women without children, but did not replace the unique social and moral responsibilities of parenting. Full article

The permanent magnet levitation (PML) transportation system utilizes Halbach arrays to achieve zero-power levitation. However, the system’s lateral negative stiffness characteristic leads to a significant increase in lateral force during operation, exacerbating lateral vibration and compromising system stability. Taking the Xingguo Line PML system as the research object, this study systematically analyzes the nonlinear characteristics of the levitation force and lateral force in a single-point levitation system through theoretical modeling, finite element simulation, and experimental validation. The concept of a ‘Magnetic Wheelset’ coupling the left and right levitation points of the bogie is proposed. The influence of five mounting forms—Aligned, X-type, Different center distance, Double V-type, and Single V-type—on the levitation performance of the Magnetic Wheelset is investigated. The coefficient of variation (CV) method is employed to evaluate force stability, and an optimal case is subsequently screened out using a dual-objective constraint approach that incorporates mean levitation force and lateral force thresholds. Results indicate that the X-type mounting at 25° is the optimal case. At 40 km/h, compared to the baseline Aligned configuration, the root mean square (RMS) values of the bogie’s vertical and lateral vibration accelerations are reduced by 14.7% and 23.8%, respectively. The vehicle’s vertical and lateral ride comfort indices decrease by 0.33 and 0.27, respectively, and the track beam’s vertical and lateral vibration accelerations are reduced by 19.4% and 13.3%. The methodology presented in this study provides a valuable reference for vibration suppression in PML systems. Full article