Search Results (533)

Entangled photons are essential for photonic quantum technologies. Their generation typically relies on spontaneous parametric down-conversion, but conventional nonlinear crystals are bulky and hard to integrate on chips. Rhombohedral-stacked MoS₂ combines a high refractive index, large second-order nonlinearity, and flexibility for heterogeneous integration, making it a promising platform for integrated quantum photonics. However, the typical thin-film form of 3R-MoS₂ restricts the effective nonlinear interaction length, limiting entanglement generation efficiency in practical devices. To overcome this, phase-matching strategies in integrated waveguides are required but have so far remained undeveloped. Here, we introduce a waveguide-integrated 3R-MoS₂ platform with periodic grooves to achieve quasi-phase matching, enhancing down-conversion efficiency. Leveraging ${\chi }^{\left(2\right)}$ tensor symmetries and orthogonal waveguide modes, the design efficiently generates entangled photons, providing a compact, scalable route toward 2D-material-based integrated quantum photonic circuits. Full article

With regard to low-voltage (LV) distribution networks, the quality of distributed electricity can be compromised by the level of phase load imbalance. Consequently, numerous phase load balancing (PLB) algorithms have been proposed in the specialized literature. However, those models have been focused on the quality of the solution obtained rather than performance, which leads to reduced practical applicability for the distribution network (reduced scalability, slow convergence, and a higher computational cost). Furthermore, certain constraints regarding the electrical network and the switching operations of consumers must be integrated into the mathematical model. In this context, the proposed PLB algorithm represents an improved constrained greedy optimization (ICGO), capable of achieving fast convergence even on large datasets, with a lower computational cost. Three scenarios (30, 250, and 500 consumers), each with 20 distinct initial non-symmetries, were simulated. The results support the practical effectiveness and scalability of the ICGO: an absolute value of the neutral current below 0.63 A (99.53% relatively reduction), a current unbalance index below 0.1%, a small number of iterations (between 4 and 11 iterations), and an execution time between 0.00051 and 0.01149 s). Therefore, this research proposes an efficient PLB algorithm, with the possibility for its improvement in future work. Full article

As the core component of new energy vehicles, the performance of the steering axle will directly affect the overall maneuverability, stability, and safety of vehicle driving. The structural performance indexes of the steering axle of the pure electric vehicle are analyzed by the finite element method, and a reasonable improvement plan is given according to its shortcomings. Firstly, the 3D model of the steering axle is established by SolidWorks (SOLIDWORKS 2023), and the details are simplified appropriately and then imported into the ANSYS (ANSYS2020R2 software) platform for static force analysis and modal analysis. Then, the stress distribution, deformation, and the first six orders of intrinsic frequency values of the steering axle are calculated and analyzed by using four working conditions, such as regular driving, emergency braking, lateral slip, and uneven road excitation, and it is concluded that the maximum stress of the original structure under each working condition is less than the requirement of the ultimate stress value. However, from the results, the maximum stress value is concentrated in the emergency braking condition and appears in the intermediate beam corner and the steering knuckle journal, which is also the most dangerous condition. In the modal analysis, it is concluded that the intrinsic frequency of this symmetry structure is much larger than the excitation frequency, and it can produce better dynamic effects under the working conditions, and the dynamic performance is better. Based on this, combined with the results of the static analysis of the proposed new increase in the thickness of the intermediate beam to improve the structural strength of the improvement measures, for this symmetry structure, through the re-simulation of the effect of the most critical conditions (emergency braking), the maximum deformation of the steering axle has been greatly reduced. In addition, the overall stiffness of the symmetry structure has been greatly improved, while the maximum stress is still less than the value of the permissible stress range, and the modal characteristics of the structure has not been affected. The finite element analysis software can effectively evaluate the performance and improve the optimization of the steering axle, which has certain theoretical significance and engineering reference value. Full article

Background: Breast reconstruction surgery (BRS) is a vital coping mechanism for patients undergoing mastectomy. Various methods have been introduced, including immediate and delayed-immediate BRS. This study employs a smartphone-based approach for three-dimensional (3D) surface imaging to compare outcomes after immediate vs. delayed-immediate BRS. Methods: Twenty-six patients who underwent BRS using the deep inferior epigastric perforator (DIEP) flap at our institution from 1 October 2018 to 1 October 2023 were included in this study. Thirteen patients underwent immediate BRS and thirteen underwent delayed-immediate BRS. Following successful BRS, each patient underwent a digital anthropometric examination that included 14 measurements and the calculation of the symmetry index (SI) using the iPhone 15 Pro along with the 3D Scanner App and the Vectra Analysis Module (VAM). Measurements were subsequently compared between immediate and delayed-immediate BRS using the t-test for independent samples. Results: For 11 of 14 measurements, no significant differences were detected between immediate and delayed-immediate BRS. The SI did not differ significantly between immediate (M = 0.85) and delayed-immediate (M = 0.88) BRS (t-test for independent samples; p = 0.23, n = 26, two-tailed). Additionally, no significant differences were found between patients’ age, height, weight, BMI, time since first diagnosis, and flap weight using a t-test for independent samples. Conclusions: No statistically significant differences in breast symmetry were detected between immediate and delayed-immediate reconstruction in this cohort. This study supports the integration of smartphone-based 3D imaging into routine plastic surgery. Full article

We present a concise and self-contained extension of the Finite Ring Continuum (FRC) program, showing that symmetry-complete prime shells ${\mathbb{F}}_{\mathsf{p}}$ with $\mathsf{p}=4\mathsf{t}+1$ exhibit a fundamental Euclidean-Lorentzian dichotomy. A genuine Lorentzian quadratic form cannot be realized within a single space-like prime shell ${\mathbb{F}}_{\mathsf{p}}$, since to split time from space one requires a time coefficient $c^2$ in the nonsquare class of ${\mathbb{F}}_{\mathsf{p}}^{\times }$, but then $c\notin {\mathbb{F}}_{\mathsf{p}}$. An explicit finite-field Lorentz transformation is subsequently derived that preserves the Minkowski form and generates a finite orthogonal group $O(Q_{\nu },{\mathbb{F}}_{p^2})$ of split type (Witt index 1). These results demonstrate that the essential algebraic features of special relativity—the invariant interval and Lorentz symmetry—emerge naturally within finite-field arithmetic, thereby establishing an intrinsic relativistic algebra within FRC. Finally, this dichotomy implies the algebraic origin of causality: Euclidean invariants reside within a space-like shell ${\mathbb{F}}_{\mathsf{p}}$, while Lorentzian structure and causal separation arise in its quadratic spacetime extension ${\mathbb{F}}_{{\mathsf{p}}^2}$. Full article

This paper addresses the cold-start problem and rare event prediction challenges in Olympic medal forecasting by proposing a predictive framework that integrates multi-granularity transfer learning with extreme value theory. The framework comprises two main components, a Multi-Granularity Transfer Learning Core (MG-TLC) and a Rare Event Analysis Module (RE-AM), which address multi-level prediction for data-scarce countries and first medal prediction tasks. The MG-TLC incorporates two key components: Dynamic Feature Space Reconstruction (DFSR) and the Hierarchical Adaptive Transfer Strategy (HATS). The RE-AM combines a Bayesian hierarchical extreme value model (BHEV) with piecewise survival analysis (PSA). Experiments based on comprehensive, licensed Olympic data from 1896–2024, where the framework was trained on data up to 2016, validated on the 2020 Games, and tested by forecasting the 2024 Games, demonstrate that the proposed framework significantly outperforms existing methods, reducing MAE by 25.7% for data-scarce countries and achieving an AUC of 0.833 for first medal prediction, 14.3% higher than baseline methods. This research establishes a foundation for predicting the 2028 Los Angeles Olympics and provides new approaches for cold-start and rare event prediction, with potential applicability to similar challenges in other data-scarce domains such as economics or public health. From a symmetry viewpoint, our framework is designed to preserve task-relevant invariances—permutation invariance in set-based country aggregation and scale robustness to macro-covariate units—via distributional alignment between data-rich and data-scarce domains and Olympic-cycle indexing. We treat departures from these symmetries (e.g., host advantage or event-program changes) as structured asymmetries and capture them with a rare event module that combines extreme value and survival modeling. Full article

Forecasting real-world time series in domains with strong event sensitivity and regional variability poses unique challenges, as predictive models must account for sudden disruptions, heterogeneous contextual factors, and structural differences across locations. In tackling these challenges, we draw on the concept of symmetry that refers to the balance and invariance patterns across temporal, multimodal, and structural dimensions, which help reveal consistent relationships and recurring patterns within complex systems. This study is based on two multimodal datasets covering 12 tourist regions and more than 3 years of records, ensuring robustness and practical relevance of the results. In many applications, such as monitoring economic indicators, assessing operational performance, or predicting demand patterns, short-term fluctuations are often triggered by discrete events, policy changes, or external incidents, which conventional statistical and deep learning approaches struggle to model effectively. To address these limitations, we propose an event-aware multimodal time-series forecasting framework with graph-based regional transfer built upon an enhanced PatchTST backbone. The framework unifies multimodal feature extraction, event-sensitive temporal reasoning, and graph-based structural adaptation. Unlike Informer, Autoformer, FEDformer, or PatchTST, our model explicitly addresses naive multimodal fusion, event-agnostic modeling, and weak cross-regional transfer by introducing an event-aware Multimodal Encoder, a Temporal Event Reasoner, and a Multiscale Graph Module. Experiments on diverse multi-region multimodal datasets demonstrate that our method achieves substantial improvements over eight state-of-the-art baselines in forecasting accuracy, event response modeling, and transfer efficiency. Specifically, our model achieves a 15.06% improvement in the event recovery index, a 15.1% reduction in MAE, and a 19.7% decrease in event response error compared to PatchTST, highlighting its empirical impact on tourism event economics forecasting. Full article

Location-based services (LBSs), which are used for navigation, tracking, and mapping across digital devices and social platforms, establish a user’s position and deliver tailored experiences. Collecting and sharing such trajectory datasets with analysts for business purposes raises critical privacy concerns, as both symmetry in recurring behavior mobility patterns and asymmetry in irregular movement mobility patterns in sensitive locations collectively expose highly identifiable information, resulting in re-identification risks, trajectory disclosure, and location inference. In response, several privacy preservation models have been proposed, including k-anonymity, l-diversity, t-closeness, LKC-privacy, differential privacy, and location-based approaches. However, these models still exhibit privacy issues, including sensitive location inference (e.g., hospitals, pawnshops, prisons, safe houses), disclosure from duplicate trajectories revealing sensitive places, and the re-identification of unique locations such as homes, condominiums, and offices. Efforts to address these issues often lead to utility loss and computational complexity. To overcome these limitations, we propose a new ($\xi$, $ϵ$)-privacy model that combines data generalization and suppression with sliding windows and R-Tree structures, where sliding windows partition large trajectory graphs into simplified subgraphs, R-Trees provide hierarchical indexing for spatial generalization, and suppression removes highly identifiable locations. The model addresses both symmetry and asymmetry in mobility patterns by balancing generalization and suppression to protect privacy while maintaining data utility. Symmetry-driven mechanisms that enhance resistance to inference attacks and support data confidentiality, integrity, and availability are core requirements of cryptography and information security. An experimental evaluation on the City80k and Metro100k datasets confirms that the ($\xi$, $ϵ$)-privacy model addresses privacy issues with reduced utility loss and efficient scalability, while validating robustness through relative error across query types in diverse analytical scenarios. The findings provide evidence of the model’s practicality for large-scale location data, confirming its relevance to secure computation, data protection, and information security applications. Full article

Background and Objectives: Partial gluteal tendon tears in native hips are often misdiagnosed as greater trochanteric pain syndrome, resulting in ineffective conservative treatment and persistent symptoms. Although surgical repair techniques exist, data on objective strength outcomes in non-arthritic hips remain limited. The objective of this study was to evaluate pain reduction, patient-reported outcomes (PROMs), and isometric hip abductor strength following mini-open, knotless double-row repair using the Hip Bridge technique. Material and Methods: This retrospective, single-center cohort study (Level III) with prospective outcome evaluation included 27 patients (mean age 53 years, BMI 27 kg/m²) with partial gluteal tendon tears and no advanced osteoarthritis (Tönnis grade ≤ 1), treated between 2015 and 2022 using the mini-open, knotless double-row Hip Bridge technique. The mean follow-up was 29.3 ± 24.3 months (minimum 6 months). Diagnosis was confirmed by 3-Tesla MRI, and other sources of lateral hip pain were excluded. Clinical outcomes included the Visual Analog Scale (VAS), modified Harris Hip Score (mHHS), Hip Outcome Score (HOS), normalized Western Ontario and McMaster Universities Osteoarthritis Index (nWOMAC), and Copenhagen Hip and Groin Outcome Score (HAGOS). Isometric hip abductor strength was assessed in 22 patients using a dynamometer, comparing the operated and contralateral limbs. Results: Postoperative satisfaction was high: 93% would undergo surgery again, 88% reported improved Trendelenburg gait, and 85% noted subjective strength gains. Pain improved significantly from VAS 8 (range, 3 to 10) preoperatively to VAS 2 (range, 0 to 7) postoperatively (p < 0.001); 100% reported pain relief. Patient-reported outcome scores were mHHS, 84.2; nWOMAC, 86.5; HOS, 80.7; and HAGOS, 70.7. Isometric strength testing showed significant improvement on the operated side (Fmax: p = 0.006; Fmean: p = 0.009). The mean limb symmetry index was 118% for Fmax and 122% for Fmean. Conclusions: Mini-open, knotless double-row repair of partial gluteal tears in non-arthritic hips yields adequate pain relief, high satisfaction, and objective strength recovery. The Hip Bridge technique could be an effective option after failed conservative treatment. Future prospective comparative studies are warranted to validate mid-term outcomes and establish long-term efficacy. Full article

Background: Foot morphology plays a central role in musculoskeletal development during childhood. Variations in the medial longitudinal arch may influence walking mechanics, and excess body weight can further affect plantar structure and gait. Objective: This study examined the relationship between foot type, body mass index (BMI), and gait function in school-aged children, with particular focus on gait symmetry as a sensitive marker. Methods: Ninety-eight children aged 8–16 years were evaluated. Foot type was classified using a pressure platform, and gait was assessed with a wearable sensor. Outcomes included gait symmetry, walking speed, cadence, Timed Up and Go (TUG), and Six-Minute Walk Distance (6MWD). Results: Mixed bilateral foot patterns were observed in 46 of the 98 participants (47%). Significant associations were found between foot type, BMI, and gait symmetry (p < 0.01), while other mobility measures (speed, cadence, TUG, 6MWD) remained stable across groups. Children with normal bilateral feet showed the best gait symmetry, whereas mixed patterns had the lowest. Conclusions: Gait symmetry is a sensitive indicator of functional imbalance in schoolchildren and is strongly influenced by both foot morphology and body weight. Incorporating plantar assessment and BMI monitoring into routine pediatric evaluations may help clinicians identify children at risk for long-term musculoskeletal problems at an early stage. Full article

Objectives: There is a growing interest among practitioners in employing artificial intelligence (AI) to enhance the precision and efficiency of diagnostic methods. The objective of this study is to assess the precision of an AI-based method for facial asymmetry assessment using 3D facial images. Methods: The study included 130 patients (84 female, 46 male), analyzing 3D facial images from the Vectra^® M3 imaging system using both manual and AI-based methods. Seven bilateral facial landmarks were identified for manual analysis, calculating the asymmetry index for facial symmetry assessment. An AI-based program was developed to automate the identification of the same landmarks and calculate the asymmetry index. The reliability of the manual measurements was assessed using intraclass correlation coefficients (ICC) with 95% confidence intervals (CI). Precision of automated landmark identification was compared to the manual method. Results: The ICCs for the manual measurements demonstrated moderate to excellent reliability, both within raters (ICC = 0.62–0.99) and between raters (ICC = 0.72–0.96) each calculated with 95% CI. Agreement was observed between the manual and automated methods in calculating the asymmetry index for five landmarks. There was a statistically significant difference between the two methods in determining the asymmetry index for alare (median: 2.05 mm manual vs. 1.54 mm automated, p = 0.0056) and cheilion (median: 2.77 mm manual vs. 2.30 mm automated, p = 0.0081). Conclusions: The AI-based method provides efficient and comparable precision of facial asymmetry analysis using 3D images. The disagreement observed between the two methods can be addressed through further improvement and training of the automated software. This innovative approach opens doors to significant advancements in both research and clinical orthodontics. Full article

An approximate optimal control issue for modular unmanned systems (MUSs) is presented via a cooperative differential game for solving the trajectory tracking problem. Initially, the modular unmanned system’s dynamic model is built with the joint torque feedback technique. The moment of inertia of the motor rotor has positive symmetry. Each MUS module is deemed as a participant in the cooperative differential game. Then, the MUS trajectory tracking problem is transformed into an approximate optimal control problem by means of adaptive critic design (ACD). The approximate optimal control is obtained by the critic network, approaching the joint performance index function of the system. The stability of the closed-loop system is proved through Lyapunov theory. The feasibility of the proposed control algorithm is verified by an experimental platform. Full article

Background: Despite the high prevalence of anterior cruciate ligament (ACL) surgeries, standardized, evidence-based rehabilitation protocols remain lacking. Digital medical devices (DMDs) like the “Orthelligent” system have gained relevance as adjuncts to traditional physiotherapy, offering continuous, objective monitoring of functional recovery. Methods: A retrospective cohort analysis included 335 patients who underwent ACL reconstruction and used the “Orthelligent home” system between August 2022 and December 2024. In total, 5675 recorded test and exercise events were analyzed. Functional recovery was assessed using the Limb Symmetry Index (LSI) across five defined rehabilitation phases (0–4). All patients followed a structured rehabilitation program aligned with current clinical practice guidelines, supplemented by Orthelligent as a home-based digital tool for daily monitoring. Results: Significant functional improvement was observed during early rehabilitation phases, with the LSI increasing from 0.64 ± 0.02 in phase 0 to 0.81 ± 0.01 in phase 2 (p < 0.001). Time since surgery was a significant positive predictor (p = 0.034), while pain showed a strong negative impact on performance (p < 0.001). Anthropometric factors had no significant effect. Exercises associated with high rates of drop-out, pain, or difficulty were identified and linked to specific rehab phases. Conclusions: This study demonstrates that digital rehabilitation monitoring can reliably reflect patient progress after ACL reconstruction. The early postoperative period (first 3 months) is critical for functional gains, highlighting the need for individualized, pain-sensitive rehabilitation strategies. Full article

Background: Hamstring tendon autografts are frequently used for anterior cruciate ligament reconstruction (ACLR), but they are associated with persistent hamstring strength deficits and delayed functional recovery. Current rehabilitation guidelines often delay open kinetic chain (OKC) hamstring exercises due to safety concerns, despite the limited supporting evidence. This uncontrolled, underpowered, and exploratory study aimed to evaluate the safety and effectiveness of introducing OKC hamstring strengthening exercises as early as three weeks after ACLR. Methods: An exploratory retrospective observational study was conducted at a single physiotherapy center on 13 patients (aged 18–35) who underwent primary ACLR with semitendinosus–gracilis grafts. Participants followed a standardized rehabilitation program including isometric leg curls at 60° and 90° knee flexion and long-lever glute bridges twice weekly, starting from postoperative week 3. Safety was assessed through predefined “safety flags” (pain > 4/10, hematoma, clinical hamstring strain). Strength outcomes, including isometric knee flexion strength at 60° and 90°, limb symmetry index (LSI), and endurance tests, were assessed at 6 and 12 weeks. Results: All participants completed the program without major adverse events. Pain remained consistently low (median 2.5/10), with only one transient episode exceeding the threshold. No other complications were recorded. Isometric knee flexion strength significantly improved between week 6 and week 12 at both 60° (p = 0.018) and 90° (p = 0.003), with large effect sizes. LSI at 90° also increased significantly (p = 0.006), whereas improvements at 60° did not reach significance. Endurance testing showed functional gains as early as 6 weeks. Conclusions: The early introduction of OKC hamstring strengthening exercises three weeks after ACLR with hamstring autografts appears safe and promotes clinically meaningful improvements in strength and endurance. These findings, while from a small uncontrolled study, challenge conservative rehabilitation protocols and support the reconsideration of early hamstring loading. Given the retrospective, uncontrolled, and underpowered design, these findings are hypothesis-generating and not generalizable beyond young adults with hamstring autografts; larger randomized trials are required. Full article

To elucidate the fatigue damage evolution of solar road panels under long-term loading and enhance their structural durability, this study develops a particle-based discrete element model and simulates fatigue responses under different structural configurations and loading rates. A strength degradation index was established by introducing peak stress and terminal stress, enabling quantitative evaluation of strength deterioration. Combined with fracture evolution, the dominant mesoscopic damage mechanisms were revealed. The results indicate that structural configuration strongly influences fatigue performance, with square panels showing the best resistance due to geometric symmetry and stable boundary constraints. Loading rate regulates damage evolution: lower rates promote structural coordination but may delay cumulative failure, while higher rates suppress overall deformation yet increase localized fracture risk. Based on these findings, a nonlinear predictive model of the strength degradation rate was constructed (R² = 0.935), offering reliable support for structural life prediction and design optimization. Finally, fatigue-resistant design strategies are proposed, including optimal structural configuration, controlled loading rates, bonding enhancement, and integration of online monitoring—providing both theoretical and technical guidance for high-performance, long-lifespan solar road systems. Full article