Search Results (1,597)

In Global Navigation Satellite System (GNSS)-denied environments, unmanned aerial vehicles (UAVs) relying on Vision-Based Navigation (VBN) in high-altitude, mountainous terrain face severe challenges due to geometric distortions in aerial imagery. This paper proposes a georeferenced localization framework that integrates orthorectified aerial imagery with Scene Matching (SM) to achieve robust positioning. The method employs a camera projection model combined with Digital Elevation Model (DEM) to orthorectify UAV images, thereby mitigating distortions from central projection and terrain relief. Pre-processing steps enhance consistency with reference orthophoto maps, after which template matching is performed using normalized cross-correlation (NCC). Sensor fusion is achieved through extended Kalman filters (EKFs) incorporating Inertial Navigation System (INS), GNSS (when available), barometric altimeter, and SM outputs. The framework was validated through flight tests with an aircraft over 45 km trajectories at altitudes of 2.5 km and 3.5 km in mountainous terrain. The results demonstrate that orthorectification improves image similarity and significantly reduces localization error, yielding lower 2D RMSE compared to conventional rectification. The proposed approach enhances VBN by mitigating terrain-induced distortions, providing a practical solution for UAV localization in GNSS-denied scenarios. Full article

Non-precious catalysts for alkaline hydrogen evolution reaction (HER) face a fundamental multi-scale challenge: lack of synergy between electronic structure tuning for balancing H adsorption and water dissociation, active site stabilization for boosting intrinsic turnover frequency (TOF), and mass transport. Even Pt loses 2–3 orders of magnitude activity in alkaline media due to inefficient water dissociation, a synergistic gap unresolved by the Sabatier principle alone. Existing strategies only address isolated aspects: phase engineering optimizes electronic structure but not active site stability; heteroatom doping introduces defects unlinked to mass transport; and nanostructuring enhances mass transfer but not atomic-level activity. None of them address multi-scale mechanistic synergy. Herein, we design a hierarchically porous P-doped NiCo alloy (hpP-NiCo) with an aim of achieving this synergy via integrating α-FCC/ε-HCP phases, P-induced defects, and 3D porosity. The formed α/ε interface tunes the d-band center to balance H adsorption and water dissociation; and the doped P stabilizes metal-vacancy sites to boost TOF. In addition, porosity matches mass transport with active site accessibility. In 1 M KOH, hpP-NiCo reaches 1000 mA cm⁻² at 185 mV overpotential and has a Tafel slope of 43.1 mV dec⁻¹, corresponding to electrochemical desorption as the rate-limiting step and verifying Volmer acceleration. Moreover, it also exhibits bifunctional oxygen evolution reaction (OER), achieving 100 mA cm⁻² at potential of 1.55 V. This work establishes a mechanistic synergy model for non-precious HER catalysts. Full article

The aim of this study was to analyze the effects of a 24-week low-load, low-volume resistance training (RT) program combined with plyometric exercises on the physical performance of U-15 male soccer players. Thirty-two young soccer players were divided into a strength training group (STG) and a control group (CG). The STG added two RT sessions per week—using moderate loads (45–60% 1RM) and a low number of repetitions per set—combined with plyometrics to their regular soccer training, while the CG continued with only the field soccer training. Performance assessments (a running sprint test, a countermovement jump, and a progressive loading test in a full squat exercise) were conducted before and after each of three 8-week periods. Significant ‘time × group’ interaction in favor of STG was observed for T20 (p < 0.05), CMJ (p < 0.001), and all variables (p < 0.001) assessed during the full squat exercise. Significant changes between groups were observed in T10 (Post 1 and Post 3, p < 0.05), CMJ (Post 1, Post 2, and Post 3, p < 0.05–0.001), and all strength variables (Post 1, Post 2, and Post 3, p < 0.05–0.001). The findings of this study suggest that a training program based on weightlifting with light loads for a few repetitions per set combined with jumps and sprint exercises, in addition to regular soccer training, induces greater and earlier improvements in strength and sport-related actions (jumping and sprinting), compared with only field soccer training. Coaches and strength-conditioning coaches should consider using RT with low loads and low volume and performing each repetition as fast as possible as an effective stimulus to improve physical performance in key match-determining actions efficiently. Full article

Background: Optimizing training load and recovery is crucial for achieving peak performance in competitive wrestling, a sport characterized by high physical, technical, and psychological demands. Methods: This study compared the effects of two different training programs—one emphasizing high-intensity interval training (HIIT) sessions and the other based on traditional volume-oriented training—on both competitive performance and autonomic regulation measured by heart rate variability (HRV). A total of 24 elite wrestlers were divided into two equal groups, each following a different weekly training regimen over a 3-month period. HRV was recorded using a wearable 3-channel ECG Holter before training, immediately after training, and during recovery phases (up to 2 h post-exercise). HRV parameters were analyzed to assess training-induced stress and recovery status. Competitive performance was evaluated using official national championship scores and ranking positions. Results: Both training programs improved competitive performance, the HIIT-based regimen induced greater short-term suppression of parasympathetic activity (RMSSD: −32% vs. −14%; HF power: −40% vs. −18%) and increased sympathetic dominance (LF/HF: +56% vs. +22%) after training. Wrestlers in the HIIT group achieved a mean competition score of 17.92 ± 4.50 points, compared to 15.08 ± 6.26 points in the volume-oriented group. These acute autonomic shifts may provide a higher readiness for intense and explosive actions, which is advantageous in short and dynamic matches. In contrast, the volume-oriented program induced smaller acute autonomic changes but showed a slower recovery to baseline. Conclusions: These findings suggest that HRV-derived measures can serve as sensitive indicators of training load tolerance, recovery capacity, and stress susceptibility in combat sports athletes. This study highlights the value of integrating HRV monitoring into the periodization of combat training to individualize the load, prevent overtraining, and optimize performance outcomes. Full article

Background: In the Kingdom of Saudi Arabia, various COVID-19 vaccines were administered during the pandemic. However, region-specific real-word comparative data on their immunogenicity remain limited. This study aimed to assess the serological responses to Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273), and AstraZeneca (ChAdOx1 nCoV-19) vaccines in a diverse population living in KSA. Methods: This observational study included 236 adults recruited from vaccination sites in Riyadh. Participants provided serum samples at predefined intervals: before the first dose, after the first dose, after the second dose, and post-vaccination infection (if applicable). IgG and neutralising antibodies were quantified using ELISA assays. Demographic and vaccination data, and their associations with antibody responses, were evaluated. Results: At baseline, 75.4% of participants were positive for SARS-CoV-2 IgG, suggesting high prior exposure. Marked incremental increases in IgG levels were observed after each vaccine dose. Both Moderna and Pfizer elicited stronger responses, with Pfizer inducing the strongest early response and Moderna achieving the highest overall titres. Among IgG-positive individuals, neutralising antibodies were detected in 98.1%. There were no statistically significant differences by age or gender, although males tended to show higher mean titres. Heterologous vaccine schedules induced comparable or enhanced immunogenicity relative to homologous schedules, supporting their use in flexible immunisation strategies. Conclusions: All COVID-19 vaccines administered in Saudi Arabia elicited robust antibody responses, particularly the mRNA-based vaccines. Our findings support their continued use and justify varied vaccination approaches, including mix-and-match booster strategies, to enhance community immunity. Full article

Background: Monocytes can commit to different phenotypes associated with specific features required in inflammation and homeostasis. Classical and alternative activation are two extremes of monocyte polarization and are both influenced by glucocorticoids (GCs). Methods: Human monocytes were sorted from the blood of healthy individuals and activated with LPS or IL-4 and IL-13, either in the absence or presence of dexamethasone (Dex). Metabolic adjustments were analyzed using Seahorse stress tests, SCENITH, and RT-qPCR. Results: LPS enhanced glycolysis and also, to a lesser extent, oxidative phosphorylation (OXPHOS), whereas addition of Dex induced a metabolic switch in favor of the latter. In contrast, activation of monocytes with IL-4 and IL-13 exclusively stimulated OXPHOS, which was suppressed by concomitant Dex treatment. The glycolytic function of monocytes matched alterations in gene expression of glucose transporters and metabolic enzymes, which were upregulated by LPS and inhibited by Dex via interference with the mTORC1 pathway but remained unaltered in response to IL-4 and IL-13. Although the dependency of classically and alternatively activated monocytes on OXPHOS and glucose usage markedly differed, modulation by GCs was limited to the latter polarization state. Conclusions: Our findings unravel a highly selective regulation of human monocyte energy metabolism by different activating stimuli as well as by GCs. Full article

Background/Objectives: Individuals with anorexia nervosa (AN) are known to exhibit both reduced pain sensitivity—when assessed via thresholds and subjective ratings—and diminished facial expressions of emotion. Therefore, investigating the facial response to pain in this population is of particular interest. Method: Seventeen patients with AN and 18 age- and sex-matched healthy controls were assessed using a thermode to induce heat pain. Subjective pain measures included pain threshold, pain tolerance, and pain ratings of supra-threshold stimuli, rated on a numerical rating scale (NRS). Facial responses to the suprathreshold stimuli were analyzed using the Facial Action Coding System (FACS). Eating pathology was assessed using the Eating Attitudes Test (EAT-26), the Eating Disorder Inventory-2 (EDI-2) and the body mass index (BMI), while depression was measured using the Beck Depression Inventory-II (BDI-II). Results: Compared with healthy controls, AN patients showed altogether significantly reduced facial expressions of pain, with particularly pronounced reductions in Action Units AU 6_7 and AU 9_10. In contrast, subjective pain measures showed only marginal differences between groups. Importantly, the reduction in facial expression could not be accounted for by differences in pain thresholds or ratings, nor by levels of eating pathology or depression. Conclusions: Individuals with AN display a markedly reduced facial expression of pain, which was observed for the first time, consistent with similar findings regarding the facial expressions of emotions. As this reduction cannot be explained by subjective pain report, it suggests that the communication of pain is impaired on two levels in AN: both in verbal and in nonverbal signaling. This may hinder the ability of others to recognize and respond to their pain appropriately. Full article

As the environmental regulations of the International Maritime Organization (IMO) become more stringent, the accurate prediction of ship propulsion performance has become essential. Under ballast conditions where the draft is shallow, the propeller approaches the free surface, causing complex phenomena such as ventilation and surface piercing, which reduce propulsion efficiency. The conventional virtual disk (VD) method cannot adequately capture these free-surface effects, leading to deviations from model propeller results. To resolve this, a correction formula that accounts for the advance ratio (J) and submergence ratio ($h/D$) has been proposed in previous studies. In this study, the correction formula was simplified and implemented in a CFD environment using a field function, enabling dynamic adjustment of body force based on time-varying submergence depth. A comparative analysis was conducted between the conventional VD, modified VD, and model propeller using POW and self-propulsion simulations for an MR tanker and SP598M propeller. The improved method was validated in calm and regular wave conditions. The results showed that the modified VD method closely matched the performance trends of the model propeller, especially in free surface-interference conditions (e.g., $h/D$ < 0.5). Furthermore, additional validations in wave-induced self-propulsion confirmed that the modified VD method accurately reproduced the reductions in wake fraction and thrust deduction coefficient, unlike the overestimations observed with the conventional VD. These results demonstrate that the modified VD method can reliably predict propulsion performance under real sea states and serve as a practical tool in the early design stage. Full article

Exercise activates many metabolic and signaling pathways in skeletal muscle and other tissues and cells, causing numerous systemic beneficial metabolic effects. Traditionally recognized for their principal role in oxygen (O₂) transport, erythrocytes have emerged as dynamic regulators of vascular homeostasis. Beyond their respiratory function, erythrocytes modulate vascular tone through crosstalk with other cells and tissues, particularly under hypoxia and physical exercise. This regulatory capacity is primarily mediated through the controlled release in the bloodstream of adenosine triphosphate (ATP) and nitric oxide (NO), two potent vasodilators that contribute significantly to matching oxygen supply with tissue metabolic demand. Emerging evidence suggests that many other erythrocyte-released molecules may act as additional factors involved in tissue-erythrocyte crosstalk. This review highlights erythrocytes as active contributors to exercise-induced adaptations through their exocrine signaling. Full article

Cancer-induced cardiac dysfunction has become a major clinical challenge as advances in cancer therapies continue to extend patient survival. Once regarded as a secondary concern, cardiotoxicity is now recognized as a leading contributor to morbidity and mortality among cancer patients and survivors. Its pathophysiology is multifactorial, involving systemic inflammation (e.g., TNF-α, IL-6), oxidative stress driven by reactive oxygen species (ROS), neurohormonal imbalances (e.g., angiotensin II, endothelin-1), and metabolic disturbances. These mechanisms collectively promote cardiomyocyte apoptosis, atrophy, mitochondrial dysfunction, and impaired cardiac output. Cardiac complications may arise directly from cancer itself or as adverse effects of oncologic therapies such as anthracyclines, trastuzumab, and immune checkpoint inhibitors. These agents have been linked to heart failure (HF), systolic dysfunction, and cardiac atrophy, often progressing insidiously and underscoring the importance of early detection and careful monitoring. Current preventive and therapeutic strategies include pharmacological interventions such as ACE inhibitors, beta-blockers, statins, dexrazoxane, and endothelin receptor antagonists like atrasentan. Emerging compounds, particularly Withaferin A (WFA), have shown potential through their anti-inflammatory and cardiac protective properties. In addition, antioxidants and lifestyle modifications may provide supplementary cardioprotective benefits, while interventional cardiology procedures are increasingly considered in selected patients. Despite encouraging progress, standardized treatment protocols and robust long-term outcome data remain limited. Given the heterogeneity of cancer types and cardiovascular responses, a personalized and multidisciplinary approach is essential. Continued research and close collaboration between oncologists, cardiologists, and basic scientists will be the key to advancing care, reducing treatment-related morbidity, and ensuring that improvements in cancer survival are matched by preservation of cardiovascular health. Full article

The growing need for efficient and safe high-energy lithium-ion batteries (LIBs) in electric vehicles and grid storage necessitates advanced internal monitoring solutions. This work presents a comprehensive simulation model of a novel integrated optical sensor based on ethylene carbonate-filled photonic crystal fiber (EC-PCF). The proposed design synergistically combines a chirped fiber Bragg grating (FBG) and an extrinsic Fabry–Pérot interferometer (EFPI) on a multiplexed platform for the multifunctional sensing of refractive index (RI), temperature, strain, and pressure (via strain coupling) within LIBs. By matching the RI of the PCF cladding to the battery electrolyte using ethylene carbonate, the design maximizes light–matter interaction for exceptional RI sensitivity, while the cascaded EFPI enhances mechanical deformation detection beyond conventional FBG arrays. The simulation framework employs the Transfer Matrix Method with Gaussian apodization to model FBG reflectivity and the Airy formula for high-fidelity EFPI spectra, incorporating critical effects like stress-induced birefringence, Transverse Electric (TE)/Transverse Magnetic (TM) polarization modes, and wavelength dispersion across the 1540–1560 nm range. Robustness against fabrication variations and environmental noise is rigorously quantified through Monte Carlo simulations with Sobol sequences, predicting temperature sensitivities of ∼12 pm/°C, strain sensitivities of ∼1.10 pm/$\mathsf{\mu }$$\mathsf{\epsilon }$, and a remarkable RI sensitivity of ∼1200 nm/RIU. Validated against independent experimental data from instrumented battery cells, this model establishes a robust computational foundation for real-time battery monitoring and provides a critical design blueprint for future experimental realization and integration into advanced battery management systems. Full article

Developing highly permeable and selective membranes for energy-efficient CO₂/CH₄ separation remains challenging. Mixed-matrix membranes (MMMs) integrating polymer matrices with metal–organic frameworks (MOFs) offer significant potential. However, rational filler–matrix matching presents substantial difficulties, constraining separation performance. In this work, defects were engineered within fluorinated MOF ZU-61 through the partial replacement of 4,4′-bipyridine linkers with pyridine modulators, producing high-porosity HP-ZU-61 nanoparticles exhibiting a 267% BET surface area enhancement (992.9 m² g⁻¹) over low-porosity ZU-61 (LP-ZU-61) (372.2 m² g⁻¹). The HP-ZU-61/6FDA-DAM MMMs (30 wt.%) demonstrated homogeneous filler dispersion and pre-served crystallinity, achieving a CO₂ permeability of 1626 barrer and CO₂/CH₄ selectivity (33), surpassing the 2008 Robeson upper bound. Solution-diffusion modeling indicated ligand deficiencies generated accelerated diffusion pathways, while defect-induced unsaturated metal sites functioned as strong CO₂ adsorption centers that maintained solubility selectivity. This study establishes defect engineering in fluorinated MOF-based MMMs as a practical strategy to concurrently overcome the permeability–selectivity trade-off for efficient CO₂ capture. Full article

Deep-well radar telemetry over ultra-long cables suffers from strong frequency-selective attenuation and impedance drift under high temperature and pressure. We have proposed a channel-adaptive “communication + acquisition” architecture for a 7500 m borehole radar system. The scheme integrates spread-spectrum time domain reflectometry (SSTDR; m-sequence with BPSK) to monitor the cable in situ, identify termination/cable impedance, and adaptively match the load, thereby reducing reflection-induced loss. On the receiving side, we combine time domain adaptive equalization—implemented as an LMS-driven FIR filter—with frequency domain OFDM equalization based on least-squares (LS) channel estimation, enabling constellation recovery and robust demodulation over the distorted channel. The full processing chain is realized in real time on a Xilinx Artix-7 (XC7A100T) FPGA with module-level reuse and pre-stored training sequences for efficient hardware scheduling. In a field deployment in the Shunbei area at 7500 m depth, radar results show high agreement with third-party geological logs: the GR-curve correlation reaches 0.92, the casing reflector at ~7250 m is clearly reproduced, and the key bottom depth error is 0.013%. These results verify that the proposed system maintains stable communication and accurate imaging in harsh deep-well environments while remaining compact and implementable on cost-effective hardware. Full article

Background: While rhinoviruses (RVs) typically cause mild respiratory infections, their persistence during the SARS-CoV-2 pandemic, particularly in Hong Kong’s strict zero-coronavirus disease 2019 policy, revealed unexpected epidemiological patterns. Two distinct RV surges emerged despite stringent public health measures, suggesting unique transmission advantages among circulating strains. We hypothesised that RV persistence during pandemic restrictions reflected strain-specific adaptations in respiratory tract replication efficiency and/or immune evasion. Methods: We analysed RV genotypes and conducted blinded clinical severity assessment for 96 paediatric hospitalisations during 2020–2021 outbreaks, compared with 180 age- and sex-matched control subjects from the corresponding weeks in pre-pandemic years (2018–2019). RV isolates from 2020 to 2021 outbreaks were characterised for their replication competence and transcriptomic responses in primary human nasal epithelial cell (HNEC) and environmental stability assays, using RV-A16 and RV-A1B as controls. Result: Minor group genotypes RV-A47 and RV-A49 were overrepresented during these two outbreaks. RV-A49 exhibited comparable replication efficiency to RV-A16 but induced significantly stronger transcriptomic responses, notably enhanced TNF and IL-1 signalling, in HNECs, alongside robust replication competence. Our data also suggests the association of RV-A49 with tachypnoea in 2021, particularly in younger males, though limited by a small sample size and single-centre design. Conclusion: The predominance of RV-A49 in hospitalised children during the SARS-CoV-2 pandemic potentially driven by its replication competence in HNECs and its capacity to enhanced inflammatory responses. The result is hypothesis-generating, warranting further studies with historical strains and broader populations to confirm strain-specific severity. Full article

Drought-induced forest mortality threatens biodiversity globally, particularly in arid, and semi-arid woodlands. The continual development of remote sensing approaches enables enhanced monitoring of forest health. Herein, we investigate the ability of a limited ground-truthed canopy dieback dataset and satellite image derived Normalised Difference Vegetation Index (NDVI) to make inferences about forest health as temporal and spatial extent from its collection increases. We used ground-truthed observations of relative canopy mortality from the Pinus edulis-Juniperus osteosperma woodlands of southeastern Utah, United States of America, collected after the 2017–2018 drought, and PlanetScope satellite imagery. Through assessing different modelling approaches, we found that NDVI is significantly associated with sitewide mean canopy dieback, with beta regression being the most optimal modelling framework due to the bounded nature of the variable relative canopy dieback. Model performance was further improved by incorporating the proportion of J. osteosperma as an interaction term, matching the reports of species-specific differential dieback. A time-series analysis revealed that NDVI retained its predictive power for our whole testing period; four years after the initial ground-truthing, thus enabling retrospective inference of defoliation and regreening. A spatial random forest model trained on our ground-truthed observations accurately predicted dieback across the broader landscape. These findings demonstrate that modest field campaigns combined with high-resolution satellite data can generate reliable, scalable insights into forest health, offering a cost-effective method for monitoring drought-impacted ecosystems under climate change. Full article