Search Results (1,371)

Magnetorheological fluids (MRFs) exhibit dynamic, field-responsive mechanical properties, as they form chain-like and networked microstructures under magnetic stimuli. This study numerically investigates the structural and mechanical behavior of three-dimensional (3D) microbead chain assemblies, focusing on cubic and hexagonal body-centered tetragonal (BCT) configurations formed under compressive and magnetic field-driven aggregation. A finite element-based model simulates magnetostatic and stress evolution in solidified structures composed of up to 20 particle chains. The analysis evaluates magnetic flux distribution, total magnetic force, and time-resolved stress profiles under vertical loading. Results show that increasing chain density significantly enhances magnetic coupling and reduces peak stress, especially in hexagonal lattices, where early stress equilibration and superior lateral load distribution are observed. The hexagonal BCT structure exhibits superior resilience, lower stress concentrations, and faster dissipation under dynamic loads. These findings offer insights into designing energy-absorbing MRF-based materials for impact mitigation, adaptive damping, and protective microfluidic structures. Full article

Background and Objectives: Keratoconus (KC) is a progressive ectatic corneal disease that can cause irregular astigmatism and visual impairment. To describe the demographic and clinical profile of KC patients attending major eye care centers in Riyadh City, Saudi Arabia, and to explore associations with laterality, disease severity, and management patterns. Materials and Methods: This multi-center hospital-based cross-sectional study enrolled consecutive patients with a confirmed diagnosis of KC (new or follow-up) presenting between April 2022 and April 2023. All participants underwent standardized ophthalmic assessment and Scheimpflug tomography (Pentacam). Disease severity was categorized as early, moderate, or advanced using Pentacam-derived keratoconus staging, and ocular parameters (refraction, keratometry, pachymetry, and higher-order aberrations) were compared across severity categories. Results: A total of 157 patients (264 eyes) were included (mean age 31.8 years; 56.7% female), with bilateral KC in 68.2%. Eye rubbing (67.8%) and allergic symptoms (61.7%) were common. Keratometric indices and higher-order aberrations differed significantly by severity grade (p < 0.001). Management patterns differed by sex and laterality, with corneal cross-linking and glasses reported more frequently in males, and soft contact lens use concentrated among bilateral cases. Conclusions: In this hospital-based Riyadh sample, KC was often associated with eye rubbing and allergic symptoms and showed clear stage-dependent worsening of tomographic indices and optical quality. These findings support early detection and targeted counseling on modifiable behaviors, while population-based studies with non-diseased comparators are needed to quantify incidence and prevalence in Riyadh. Full article

Background: Tibial shaft fractures are frequently treated with intramedullary nailing; however, malalignment remains a concern, particularly in proximal metaphyseal fractures. The surgical approach influenced the nail entry point; however, the three-dimensional (3D) geometric characteristics of the entry point among different approaches remain unclear. Methods: This single-center retrospective study included 68 patients with acute tibial shaft fractures (AO/OTA type 42) treated with reamed and locked intramedullary nails from January 2014 to June 2024. The surgical techniques employed included lateral parapatellar (LPA, n = 31), infrapatellar (IPA, n = 27), and suprapatellar (SPA, n = 10) approaches. Postoperative computed tomography (CT) data were reconstructed into standardized 3D images. The mediolateral insertion ratio was calculated as the percentage distance from the lateral tibial plateau edge to the nail entry point relative to the plateau’s width in the coronal plane. The shortest distance from the tibial articular surface to the nail (r) was measured in the sagittal plane. The Kruskal–Wallis test and Dunn’s post hoc comparisons were used to analyze group differences. Results: Baseline patient and fracture characteristics did not significantly differ among the groups. The mediolateral insertion ratio significantly differed (p < 0.0001), with a more lateral entry for the LPA (44.0% [43.0–47.0]) than for the IPA (51.0% [49.0–53.0], post hoc p < 0.0001) and SPA (49.0% [47.0–51.3], post hoc p = 0.0034). Further, the sagittal distance r significantly differed (p < 0.0001), with a more distal entry for the LPA (14.8 [12.8–20.1] mm) than for the IPA (9.7 [7.0–11.8] mm, post hoc p < 0.0001) and SPA (10.5 [5.5–12.9] mm, post hoc p = 0.0008). No statistically significant difference was observed between the IPA and SPA. Conclusions: The LPA generates a significantly more lateral and distal tibial nail entry point than the IPA and SPA. No statistically significant differences were detected between the IPA and SPA in either plane. These 3D-CT findings may warrant attention during approach selection and guidewire placement, particularly for fractures extending into the proximal metaphysis. Full article

In the field of earthquake-resistant design, there is an increasing emphasis on evaluating buildings as integrated systems rather than as assemblies of independent components. Hybrid wall systems based on structural steel and reinforced concrete offer a promising alternative to existing approaches by combining the stiffness and toughness of concrete with the ductility and flexibility of steel, which enhances resilience and seismic performance. The objective of this scientific study is to obtain preliminary analytical estimates of the earthquake response of a prototype hybrid steel RC coupled wall building that is being developed as part of a joint research program between the National Center for Research on Earthquake Engineering (NCREE) and New Zealand’s Centre for Earthquake Resilience (QuakeCoRE). Nonlinear response history analyses were carried out on the prototype building, using scaled ground motions and nonlinear hinge properties assigned to the primary lateral force resisting elements to replicate the expected inelastic behavior of the hybrid system. The results were used to evaluate story drift demands, deformation patterns, coupling beam behavior, and buckling restrained brace behavior, providing a system-level perspective on the expected earthquake performance of the proposed hybrid wall system. To deepen the current experimental understanding of the seismic behavior of the proposed hybrid structural system, a large-scale shaking table test is planned at NCREE as the next stage of this collaborative research. Full article

Objectives: The Goel–Harms technique provides rapid stabilization and high fusion rates for atlantoaxial instability but carries a risk of neurovascular injury during lateral mass and pedicle screw insertion. Recently, 3D printing has emerged as a cost-effective and increasingly accessible tool in various surgical fields. This study aimed to compare the clinical and radiological outcomes of C1–C2 fixation using a 3D-printed template versus the free-hand technique. Methods: This retrospective cohort study included patients who underwent C1–C2 fixation with the Goel–Harms technique at two tertiary neurosurgical centers between 2021 and 2023. Operative, radiological, and functional outcomes were reviewed in 21 patients who were operated using either a patient-specific 3D-printed template applied intraoperatively (Group 1; n = 10) or the free-hand technique (Group 2; n = 11). Postoperative screw accuracy was assessed using the Gertzbein–Robbins classification. Results: A total of 84 screws were placed (Group 1: 40; Group 2: 44). In Group 1, 38 of 40 screws (95%) were accurately placed, compared with 41 of 44 screws (93.1%) in Group 2. The mean fluoroscopy and operative times were significantly shorter in Group 1 than in Group 2 (21.90 ± 4.33 s vs. 27.09 ± 13.48 s, p = 0.012; 126.60 ± 28.70 min vs. 171.36 ± 40.44 min, p = 0.010, respectively). Conclusions: The 3D-printed template technique significantly reduced operative and fluoroscopy times compared with the free-hand technique. Three-dimensional printing offers a cost-effective alternative to conventional navigation systems by eliminating their time-consuming preoperative setup in the operating room. Full article

Meniscal repair has become the preferred treatment for many meniscal tears. As a result, multiple arthroscopic techniques have evolved, including the all-inside (AI) and inside-out (IO) approaches, which have been widely studied in the current literature. The present article highlights key limitations in studies reporting long-term outcomes (≥5 years), notably the heterogeneity of failure definitions and the lack of subgroup stratification by clinically relevant factors such as age, concomitant anterior cruciate ligament reconstruction (ACLR), and meniscal side (medial vs. lateral). To date, no clear superiority of the AI over the IO approach has been established. Redefining failure through multidimensional approaches that integrate structural, clinical, and patient-reported assessments will be crucial to ensure a consistent and patient-centered evaluation of repair success. Further research with robust subgroup analyses is needed to determine whether one technique confers superior long-term results in specific patient populations. Full article

Background: In computed tomography (CT), automatic exposure control (AEC) determines the tube current and thus the radiation dose based on scout images. We investigated CT dose modulation using two versions of CARE Dose 4D, Siemens AEC software. Methods: A cylindrical phantom and an anthropomorphic phantom with the upper extremities raised or down were imaged. The CT tube current was determined using two versions of CARE Dose 4D and different scout directions: the posteroanterior scout image alone (PA scout), the lateral scout image alone (Lat scout), and the combination of the PA and Lat scout images (PA + Lat scout). The new version is designed to utilize the Lat image solely for off-center correction when both PA and Lat images are available. Experiments were performed at various vertical positions and with various scout imaging parameters. Results: The influence of the scout direction on CT dose was demonstrated, with variations depending on the imaging object and software version. The CT dose determined with the PA scout varied according to vertical positioning, presumably due to changes in image magnification. Such effects were small with the Lat scout or PA + Lat scout. Decreasing the tube voltage or tube current in scout imaging affected CT dose modulation with the Lat scout but not with the PA scout. With the PA + Lat scout, the effects of scout parameters were evident using the previous version but minimal using the new version. Conclusions: Off-center correction in the new version functioned appropriately. Because the behavior of an AEC system is complicated, it is recommended to examine the characteristics of each AEC system under various imaging conditions. 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

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/Objectives: Cystocele remains a prevalent condition with high recurrence rates following conventional native tissue repair. While mesh-based techniques may reduce anatomical recurrence, they are associated with increased complications and regulatory limitations. Our study proposes a defect-oriented approach to cystocele repair to assess whether individualized surgical management based on defect type can improve outcomes, particularly recurrence rates. Methods: A single-center retrospective analysis of 317 women undergoing cystocele repair (2019–2020) was performed. Patients were classified into five groups according to defect type: lateral defect at level II, central defect at level II, apical defect, mixed apical and lateral defects at level II, and mixed apical and central defects at level II. Surgical techniques, including vaginal mesh repair, laparoscopic or pre-peritoneal Richardson repair, sacropexy, lateral suspension, and combined procedures, were tailored to the identified defect. Postoperative outcomes and recurrence rates were assessed during follow-up visits. Results: The most common defect was apical defect at level II (35.6%) followed by lateral defect (32.8%), mixed apical and lateral (17.7%), central (8.5%), and mixed apical and central (5.4%). The most frequent procedures were vaginal mesh repair (33.8%) and laparoscopic sacropexy (28.7%). In our cohort, the overall recurrence rate was 6.3%, with the highest recurrence observed in the central defect group (11.1%) and lowest in the mixed apical and lateral defect group (0%). Conclusions: A defect-oriented classification and individualized surgical approach for cystocele enables effective, durable repair with low recurrence rates. Precise identification of the anatomical defect, rather than the routine use of hysterectomy or mesh, should guide surgical planning to optimize functional and anatomical outcomes. Full article

To address the difficulty of balancing trajectory-tracking accuracy and yaw stability for distributed-drive four-axle heavy trucks under high-speed and large-curvature cornering conditions, this paper proposes a hierarchical cooperative control strategy. The upper layer employs Sliding Mode Control (SMC) to achieve precise trajectory tracking, while the lower layer integrates a sliding-mode-based Direct Yaw Moment Control (DYC) and a differential braking allocation strategy to enhance vehicle stability. TruckSim–Simulink co-simulation results demonstrate that, under large-curvature scenarios such as S-shaped paths, sharp lane changes, and single-lane transitions, the proposed strategy outperforms the conventional SMC method. Specifically, the maximum lateral deviation is reduced by 19.23–23.02%, the peak heading angle error decreases from 5.3° to 3.5°, the maximum yaw rate drops from 12.6°/s to 4.6°/s (a 63.49% reduction), and the peak sideslip angle at the vehicle’s center of mass converges from 4.6° to 3.8° (a 17.39% decrease). The results indicate that the proposed strategy achieves coordinated optimization of trajectory tracking and yaw stability under high-speed, large-curvature cornering conditions, providing both theoretical support and engineering value for high-dynamic control of distributed-drive heavy trucks. Full article

Background: Differentiating true tumor progression (TP) from treatment-related pseudoprogression (PsP) in glioblastoma remains challenging, especially at early follow-up. Methods: We present the first timepoint-specific, cross-sectional benchmarking of deep learning models for follow-up MRI using the Burdenko GBM Progression cohort (n = 180). We analyze different post-RT scans independently to test whether architecture performance depends on timepoint. Eleven representative DL families (CNNs, LSTMs, hybrids, transformers, and selective state-space models) were trained under a unified, QC-driven pipeline with patient-level cross-validation. Across both timepoints, accuracies were comparable (~0.70–0.74), but discrimination improved at the second follow-up, with F1 and AUC increasing for several models, indicating richer separability later in the care pathway. Results: A Mamba+CNN hybrid consistently offered the best accuracy–efficiency trade-off, while transformer variants delivered competitive AUCs at substantially higher computational cost, and lightweight CNNs were efficient but less reliable. Performance also showed sensitivity to batch size, underscoring the need for standardized training protocols. Notably, absolute discrimination remained modest overall, reflecting the intrinsic difficulty of TP vs. PsP and the dataset’s size and imbalance. Conclusions: These results establish a timepoint-aware benchmark and motivate future work incorporating longitudinal modeling, multi-sequence MRI, and larger multi-center cohorts. Full article

Center of pressure is a valuable biomechanical variable, predicting joint loading contributions during movement and giving insight into compensatory patterns. The purpose of this study was to assess the validity and reliability of force insoles in calculating vertical ground reaction force and center of pressure during return-to-sport jump testing. Ten healthy individuals performed double- and single-leg vertical and horizontal jumps on an instrumented treadmill while wearing instrumented force insoles. Vertical ground reaction force and anterior–posterior and medial–lateral center of pressure were collected at peak vertical ground reaction force from both devices. Repeat testing occurred 7 ± 5 days following the initial session. Force insoles were valid for measuring vertical ground reaction force (mean absolute error (MAE): 4.34 N/kg) and anterior–posterior center of pressure (MAE: 10% foot length) but were not valid for medial–lateral center of pressure (MAE: 50% foot width). During double-leg vertical, single-leg vertical, double-leg horizontal, and single-leg horizontal jumps, force insoles demonstrated good reliability for measurements of vertical ground reaction force (ICC: 0.89, 0.75, 0.89, and 0.91), anterior–posterior center of pressure (ICC: 0.88, 0.89, 0.94, and 0.97), and medial–lateral center of pressure (ICC: 0.72, 0.09, 0.82, and 0.73). Force insoles are a valid and reliable alternative to evaluating vertical ground reaction force and anterior–posterior center of pressure during return-to-sport jump testing. Full article

Background/Objectives: American Indian/Alaska Native individuals exhibit a higher prevalence of carriage of Streptococcus pneumoniae and are at increased risk of invasive pneumococcal disease compared with the general US population, driven by persistent inequities in health determinants. Although the use of pneumococcal vaccines has reduced carriage of vaccine serotypes, the prevalence of carriage of non-vaccine serotypes has increased. Methods: This study was a descriptive subgroup analysis of the PNEU-DAY study (NCT03547167; EudraCT 2017-004915-38). Safety, tolerability, and immunogenicity of sequential administration of either V114, a 15-valent pneumococcal conjugate vaccine (PCV), or 13-valent PCV (PCV13), followed 6 months later by 23-valent pneumococcal polysaccharide vaccine (PPSV23), were evaluated in pneumococcal vaccine-naïve American Indian adults with or without pre-defined risk factors for pneumococcal disease. Polymerase chain reaction testing assessed nasopharyngeal/oropharyngeal carriage of S. pneumoniae. Results: Following administration of PCV and PPSV23, the proportions of participants with adverse events were generally comparable between vaccination groups. V114 and PCV13 were immunogenic for all respective vaccine serotypes, with V114 inducing robust immune responses to the two additional serotypes not included in PCV13 (22F and 33F), based on opsonophagocytic activity geometric mean titers and immunoglobulin G geometric mean concentrations at 30 days post-vaccination. Sequential administration with PPSV23 was immunogenic in both vaccination groups. Nasopharyngeal/oropharyngeal carriage of S. pneumoniae was observed in 16.7% to 22.6% of American Indian participants across the study timepoints. Conclusions: V114 was well tolerated and immunogenic for the 15 serotypes in V114 when administered either alone or followed by PPSV23. Use of V114 has the potential to expand serotype coverage and protect against pneumococcal disease resulting from serotypes absent in PCV13 among American Indian adults. Full article

Background: Early-onset neonatal sepsis (EONS), defined as systemic infection occurring within the first 72 hours of life, remains a major cause of morbidity and mortality in preterm infants. Increasing evidence indicates that the gut may play an active role in systemic inflammation, yet the temporal behavior of fecal short-chain fatty acids (SCFAs) during EONS has not been characterized. SCFAs and branched-chain fatty acids (BCFAs) are key microbial metabolites involved in epithelial maturation and immune regulation and may provide a non-invasive window into early inflammatory vulnerability. Methods: This pilot prospective longitudinal cohort study enrolled 49 preterm infants (≤32 weeks’ gestation) originally identified as at high risk for necrotizing enterocolitis (NEC) and subsequently stratified into EONS and non-sepsis groups. Serial stool samples were collected at predefined timepoints (TPs; TP1 ≈ 3 days of life [DoL], TP2 ≈ 7 DoL, TP3 ≈ 14 DoL, TP4 ≈ 21 DoL, and TP5 ≈ 28 DoL). Samples were analyzed using gas chromatography–mass spectrometry (GC–MS) to quantify a panel of 12 SCFAs, including BCFAs and medium-chain fatty acids (MCFAs). Both absolute concentrations and relative fractions were evaluated, with emphasis on ratio-based metrics (e.g., acetic/propionic acid ratio) and timepoint-specific group contrasts, complemented by partial least squares discriminant analysis (PLS–DA). Results: At the earliest sampling window (TP1), infants with EONS exhibited distinct early changes in SCFA composition, including a significantly lower median relative fraction of acetic acid (86.6% vs. 94.5% in non-sepsis), while several non-acetate components—including propionic, valeric, and branched-chain acids—were relatively enriched. Acetate-to-non-acetate ratios were markedly reduced in EONS (e.g., acetic/propionic and acetic/isobutyric ratios), indicating an early shift away from acetate dominance. PLS–DA at TP1 demonstrated partial separation between groups, with acetic-acid depletion and non-acetate enrichment among the strongest contributors to discrimination. By later TPs, these early differences narrowed to a small subset of BCFA-related ratios and largely attenuated by the end of the first month. Conclusions: In this pilot cohort of preterm infants, EONS was associated with early, structured alterations in fecal SCFA profiles, characterized by reduced acetic-acid dominance and relative enrichment of non-acetate acids. Dynamic, ratio-based assessment proved more informative than absolute concentrations alone, revealing transient intestinal metabolic signatures accompanying systemic infection. These findings provide the first longitudinal evidence of gut metabolic involvement in EONS and lay the groundwork for larger, multi-center studies integrating SCFA trajectories with microbiome and immune profiling to refine early risk stratification for systemic infection in high-risk neonatal populations. Full article