Search Results (2,302)

The limited availability of powerful, tunable, and reliable mid-infrared sources has historically prevented their widespread adoption in spectroscopy applications, even if most greenhouse gases’ fundamental absorption lines are found in this region of the electromagnetic spectrum. However, both mid-infrared fiber lasers and ICLs have enjoyed substantial growth in available output powers in recent years. Since the two technologies have complementary benefits, combining them could prove to be an interesting avenue to explore toward the development of a powerful, easily tunable, and narrow linewidth mid-infrared source. We report what we believe to be the first demonstration of fiber amplification of a distributed feedback interband cascade laser (DFB-ICL) operating in the mid-infrared. The system, based on an in-band pumped dysprosium-doped fluoride fiber amplifier, yields 10 dB of gain and up to 30 mW of output power at 3240 nm. We believe this is an important milestone toward power scaling of single-mode, single-frequency, and rapidly tunable mid-infrared laser sources suitable for advanced gas spectroscopy. Full article

Particle accelerators are powerful tools in fundamental research, medicine, and industry that provide high-energy beams that can be used to study matter and to enable advanced applications. The state-of-the-art particle accelerators are fundamentally constructed from superconducting radio-frequency (SRF) cavities, which act as resonant structures for the acceleration of charged particles. The performance of such cavities is governed by inherent superconducting material properties such as the transition temperature, critical fields, penetration depth, and other related parameters and material quality. For the last few decades, bulk niobium has been the preferred material for SRF cavities, enabling accelerating gradients on the order of ~50 MV/m; however, its intrinsic limitations, high cost, and complicated manufacturing have motivated the search for alternative strategies. Among these, sputter-deposited superconducting thin films offer a promising route to address these challenges by reducing costs, improving thermal stability, and providing access to numerous high-T_c superconductors. This review focuses on progress in sputtered superconducting materials for SRF applications, in particular Nb, NbN, NbTiN, Nb₃Sn, Nb₃Al, V₃Si, Mo–Re, and MgB₂. We review how deposition process parameters such as deposition pressure, substrate temperature, substrate bias, duty cycle, and reactive gas flow influence film microstructure, stoichiometry, and superconducting properties, and link these to RF performance. High-energy deposition techniques, such as HiPIMS, have enabled the deposition of dense Nb and nitride films with high transition temperatures and low surface resistance. In contrast, sputtering of Nb₃Sn offers tunable stoichiometry when compared to vapour diffusion. Relatively new material systems, such as Nb₃Al, V₃Si, Mo-Re, and MgB₂, are just a few of the possibilities offered, but challenges with impurity control, interface engineering, and cavity-scale uniformity will remain. We believe that future progress will depend upon energetic sputtering, multilayer architectures, and systematic demonstrations at the cavity scale. Full article

Structural variation (SV) serves as a fundamental driver of phenotypic diversity and environmental adaptation in plants and animals, significantly influencing key agronomic traits in crops. Common wheat (Triticum aestivum L.), an allohexaploid species, harbors extensive chromosomal SVs and distant hybridization-induced recombination events that provide critical resources for genetic improvement. This study utilizes non-denaturing fluorescence in situ hybridization (ND-FISH) and oligonucleotide multiplex probe-based FISH (ONPM-FISH) to analyze the karyotypes of 153 BC₁F₄–BC₁F₆ lines derived from the hybrid line Xiaoyan 7430 and common wheat Yannong 1212. The results revealed that Xiaoyan 7430 carries 8 alien chromosome pairs and 20 wheat chromosome pairs (lacking 6B), and Yannong 1212 contains 21 pairs of wheat chromosomes. The parental lines exhibited presence/absence variations (PAVs) on chromosomes 2A, 6A, 5B, 1D, and 2D. Chromosomal variations, including numerical chromosomal variation (NCV), structural chromosomal variation (SCV), and complex chromosomal variation (CCV), were detected in the progeny lines through ONPM-FISH analysis. The tracking of alien chromosomes over three consecutive generations revealed a significant decrease in transmission frequency, declining from 61.82% in BC₁F₄ to 26.83% in BC₁F₆. Telosomes were also lost during transmission, declining from 21.82% in BC₁F₄ to 9.76% in BC₁F₆. Alien chromosome 1J^S, 4J, and 6J exhibited the highest transmission stability and were detected across all three generations. Association analysis showed that YN-PAV.2A significantly affected the length/width ratio (LWR) and grain diameter (GD); YN-PAV.6A, XY-PAV.6A, and PAV.5B increased six grain traits (+2.25%~15.36%); YN-PAV.1D negatively affected grain length (GL) and grain circumference (GC); and XY-PAV.2D exerted positive effects on thousand-grain weight (TGW). Alien chromosomes differentially modulated grain characteristics: 1J^S and 6J both reduced grain length and grain circumference; 1J^S increased LWR; and 4J negatively impacted TGW, grain width (GW), GD, and grain area (GA). Meanwhile, increasing alien chromosome numbers correlated with progressively stronger negative effects on grain traits. These findings elucidate the genetic mechanisms underlying wheat chromosomal variations induced by distant hybridization and their impact on wheat grain traits, and provide critical intermediate materials for genome design breeding and marker-assisted selection in wheat improvement. Full article

Research on Mesoscale Convective Systems (MCSs) in Ecuador has focused on regional studies. However, it lacks a thorough and general examination of their relationship with the nation’s diverse orography and large-scale phenomena. This study conducts a climatological analysis of MCS occurrence throughout Ecuador’s natural regions. We perform this study using Sen’s Slope and the Mann–Kendall test. Teleconnections from the Pacific and Atlantic Oceans are studied through wavelet decomposition between time series and Pacific and Atlantic oceanic indices. The main factors that control MCS formation depend on the region. The Intertropical Convergence Zone (ITCZ) at the large scale affects the entire territory. In western Ecuador, MCS formation is mostly related to the El Niño current and the Chocó Low-Level Jet (CLLJ). The Orinoco Low-Level Jet (OLLJ) and evapotranspiration and nocturnal convection display the largest roles in the east. A progressive intensification of activity from Highlands-North in SON is detected (0.143 MCSs per year). MCSs contribute 26% of total precipitation on average, with regional variations from Coast-South (16.41%) to Amazon-North (44.13%). The research confirms existing knowledge about El Niño’s strong relationship (ρ = 0.7) with MCS occurrence in coastal areas while uncovering new complex patterns. The Trans-Nino Index (TNI) functions as a critical two-sided modulator that conventional analysis methods fail to detect. It produces null correlations over conventional time series of MCS occurrence yet emerges as a primary driver of low-frequency variability in the proposed six natural zones of Ecuador. Wavelet decomposition reveals contrasting TNI responses: Amazon-North shows positive correlation (0.73) while Amazon-South exhibits negative correlation (−0.70) at low frequencies. This affects Walker circulations dynamics over the Pacific Ocean. This research establishes fundamental knowledge about MCSs in Ecuador. It builds on a database with strong methodology as a backbone. The research provides essential information about the factors leading to convection in the country. This will help improve seasonal forecast accuracy and risk management effectiveness. Full article

There are close relationships between vertical positions in space and auditory experiences of fundamental frequency (F0), which even very young children seem to use. Like adults, they associate higher or rising F0 values with upper positions in space and vice versa for lower or falling F0 values. Here, we tested whether caregivers’ speech capitalizes on these associations to guide the attention of very young children (18 to 24 months). Together with their child, caregivers saw four different objects (in the corners of a computer screen). Caregivers produced standardized sentences (e.g., “Look at the hat.”). We observed a significantly increased maximum F0 (but no differences in mean or minimum F0) at the onset of the utterance when the to be named object appeared at an upper position compared to the same object at a lower position. Furthermore, exploratory analyses of F0 dynamics of caregivers’ utterances indicated that the higher F0 maximum was part of a more prominent F0 increase for objects appearing at an upper compared to a lower position. Adults without a child present and less experience in interacting with children did not show systematic pitch modulation when addressing an imagined child in the same study set-up. Thus, caregivers appear to systematically modulate F0 dynamics to provide an effective language environment when they are interacting with their child. Full article

In this article, the mechanism of relaxation polarization currents occurring at a constant temperature (isothermal process) in crystals with ionic-molecular chemical bonds (CIMBs) in an alternating electric field was investigated. Methods of the quasi-classical kinetic theory of dielectric relaxation, based on solutions of the nonlinear system of Fokker–Planck and Poisson equations (for the blocking electrode model) and perturbation theory (by expanding into an infinite series in powers of a dimensionless small parameter) were used. Generalized nonlinear mathematical expressions for calculating the complex amplitudes of relaxation modes of the volume-charge distribution of the main charge carriers (ions, protons, water molecules, etc.) were obtained. On this basis, formulas for the current density of relaxation polarization (for transient processes in a dielectric) in the k-th approximation of perturbation theory were constructed. The isothermal polarization currents are investigated in detail in the first four approximations (k = 1, 2, 3, 4) of perturbation theory. These expressions will be applied in the future to compare the results of theory and experiment, in analytical studies of the kinetics of isothermal ion-relaxation (in crystals with hydrogen bonds (HBC), proton-relaxation) polarization and in calculating the parameters of relaxers (molecular characteristics of charge carriers and crystal lattice parameters) in a wide range of field parameters (0.1–1000 MV/m) and temperatures (1–1550 K). Asymptotic (far from transient processes) recurrent formulas are constructed for complex amplitudes of relaxation modes and for the polarization current density in an arbitrary approximation k of perturbation theory with a multiplicity r by the polarizing field (a multiple of the fundamental frequency of the field). The high degree of reliability of the theoretical results obtained is justified by the complete agreement of the equations of the mathematical model for transient and stationary processes in the system with a harmonic external disturbance. This work is of a theoretical nature and is focused on the construction and analysis of nonlinear properties of a physical and mathematical model of isothermal ion-relaxation polarization in CIMB crystals under various parameters of electrical and temperature effects. The theoretical foundations for research (construction of equations and working formulas, algorithms, and computer programs for numerical calculations) of nonlinear kinetic phenomena during thermally stimulated relaxation polarization have been laid. This allows, with a higher degree of resolution of measuring instruments, to reveal the physical mechanisms of dielectric relaxation and conductivity and to calculate the parameters of a wide class of relaxators in dielectrics in a wide experimental temperature range (25–550 K). Full article

Power converters are increasingly pushing toward higher switching frequencies, with current designs typically operating between tens of kilohertz and a few megahertz. The commercialization of gallium nitride (GaN) power transistors has opened new possibilities, offering performance far beyond the limitations of conventional silicon devices. Despite this promise, the potential of GaN technology remains underutilized. This paper explores the feasibility of achieving sub-gigahertz switching frequencies using GaN-based switch-mode power converters, a regime currently inaccessible to silicon-based counterparts. To reach such operating speeds, it is essential to understand and quantify the intrinsic frequency limitations imposed by GaN device physics and associated parasitics. Existing power conversion topologies and control techniques are unsuitable at these frequencies due to excessive switching losses and inadequate drive capability. This work presents a detailed, systematic study of GaN transistor behavior at high frequencies, aiming to identify both fundamental and practical switching limits. A compact analytical model is developed to estimate the maximum soft-switching frequency, considering only intrinsic device parameters. Under idealized converter conditions, this upper bound is derived as a function of internal losses and the system’s target efficiency. From this, a soft-switching figure of merit is proposed to guide the design and layout of GaN field-effect transistors for highly integrated power systems. The key contribution of this study lies in its analytical insight into the performance boundaries of GaN transistors, highlighting the roles of parasitic elements and loss mechanisms. These findings provide a foundation for developing next-generation, high-frequency, chip-scale power converters. Full article

This article presents an extensive experimental investigation of the dynamic characteristics of three-arch historical masonry bridges, using Operational Modal Analysis (OMA). The research thoroughly characterizes the dynamic behavior of four representative masonry bridges from the Apulia Region in Southern Italy through detailed experimental campaigns. These campaigns employed calibrated and optimally implemented accelerometric monitoring systems to acquire high-quality dynamic data under controlled excitation and environmental conditions. The selected bridges include the Santa Teresa Bridge in Bitonto, the Roman Bridge in Bovino, the Roman Bridge in Ascoli Satriano and a moderner road bridge on the Provincial Road SP123 in Troia; they span almost two millennia of construction history. The experimental framework incorporated several non-invasive excitation methods, including controlled vehicle passes, instrumented hammer impacts and ambient vibration tests, strategically chosen for optimal signal quality and heritage preservation. This investigation demonstrates the feasibility of capturing the dynamic behavior of these complex and specific historic structures through customized sensor configurations and various excitation methods. The resulting natural frequencies and mode shapes are accurate, robust, and reliable considering the extended data set used, and have allowed a rigorous seismic assessment. Eventually, this comprehensive data set establishes a fundamental basis for understanding and predicting the seismic response of several three-span masonry bridges to accurately identify their long-term resilience and effective conservation planning of these valuable and vulnerable heritage structures. In conclusion, the data comparison enabled the formulation of a predictive equation for the identification of the first natural frequency of bridges from geometric characteristics. Full article

The detection and extraction of weak signals are crucial in various engineering and scientific fields, yet current acoustic sensing technologies are restricted by fundamental pressure detection methods. This paper proposes gradient-equivalent medium-coupled metamaterials (GEMCMs) utilizing strong wave compression and an equivalent medium mechanism to capture weak signals in complex environments and enhance target acoustic signals. Overcoming shape and impedance mismatch limitations of traditional gradient structures, GEMCMs significantly improve control performance. Experimental and numerical simulations indicate that GEMCMs can effectively enhance specific frequency components in acoustic signals, outperforming traditional gradient structures. This enhancement of specific frequency components relies on the resonance effect of the unit cell structure. By introducing acoustic resonance within a spatially wound acoustic channel, a significant amplification of weak acoustic signals is achieved. This provides a new research direction for acoustic wave manipulation and enhancement, and holds significant importance in fields such as mechanical fault diagnosis and medical diagnostics. Full article

Stimulated Brillouin scattering (SBS) suppression and phase demodulation are two fundamental issues in remote interferometric fiber sensing systems. A method is proposed for achieving simultaneous SBS suppression and phase-generated carrier (PGC) demodulation in remote interferometric fiber sensing systems, with only the use of an electro-optic phase modulator (PM). A single-frequency laser is phase-modulated by a PM to generate multi-sideband light, which can suppress SBS in long-haul fibers and generate PGC combined with the optical fiber interferometer. Then, the phase signal of the optical fiber interferometer can be demodulated by the PGC demodulation method. A detailed theoretical analysis and the experimental results are presented to confirm the feasibility of the method. The results show that the proposed method can achieve high-performance PGC demodulation with much higher bandwidth and larger dynamic range than the conventional method. Meanwhile, the SBS and its induced phase noise can be suppressed effectively. This work presents a simple setup for SBS suppression and PGC demodulation in a remote interferometric fiber sensing system. The proposed method shows great potential for application in remote and large-scale interferometric fiber sensing systems. Full article

With the breakthroughs in quantum theory and the rapid advancement of quantum precision measurement sensor technologies, atomic magnetometers based on the spin-exchange relaxation-free (SERF) mechanism have played an increasingly important role in ultra-weak biomagnetic field detection, inertial navigation, and fundamental physics research. To achieve high-precision measurements, SERF magnetometers must operate in an extremely weak magnetic field environment, while the detection of ultra-weak magnetic signals relies on a low-noise background. Therefore, accurate measurement, modeling, and analysis of magnetic noise in shielding materials are of critical importance. In this study, the magnetic noise of permalloy sheets was modeled, separated, and analyzed based on their measured magnetic properties, providing essential theoretical and experimental support for magnetic noise evaluation in shielding devices. First, a single-sheet tester (SST) was modeled via finite element analysis to investigate magnetization uniformity, and its structure was optimized by adding a supporting connection plate. Second, an experimental platform was established to verify magnetization uniformity and to perform accurate low-frequency measurements of hysteresis loops under different frequencies and field amplitudes while ensuring measurement precision. Finally, the Bertotti loss separation method combined with a PSO optimization algorithm was employed to accurately fit and analyze the three types of losses, thereby enabling precise separation and calculation of hysteresis loss. This provides essential theoretical foundations and primary data for magnetic noise evaluation in shielding devices. Full article

This study investigates the topology optimisation of a composite wind turbine blade with the objective of improving its structural performance under static and dynamic constraints. Two distinct optimisation strategies—based on static deformation limits and modal frequency enhancement—are employed to achieve mass reduction while maintaining or improving mechanical performance. The optimisation process incorporates modal characterisation of the first ten natural frequencies and a detailed static stress analysis. Results indicate that the optimised designs achieve a notable increase in the fundamental natural frequency of the blade—from 2.32 Hz to 2.99 Hz—and reduce the overall mass by approximately 49%, lowering it from 4.55 × 10⁵ kg to around 2.34 × 10⁵ kg compared to the original configuration. In particular, the optimised geometry offers improved stiffness and a more uniform stress distribution, especially in the flapwise bending and torsional modes. Higher-order torsional frequencies remain well-separated from typical excitation sources, minimising resonance risks. These findings highlight the effectiveness of constraint-driven topology optimisation in enhancing structural performance and reducing material usage in wind turbine blade design. Full article

Object detection in soccer scenes serves as a fundamental task for soccer video analysis and target tracking. This paper proposes WCC-YOLO, a symmetry-enhanced object detection framework based on YOLOv11n. Our approach integrates symmetry principles at multiple levels: (1) The novel C3k2-WTConv module synergistically combines conventional convolution with wavelet decomposition, leveraging the orthogonal symmetry of Haar wavelet quadrature mirror filters (QMFs) to achieve balanced frequency-domain decomposition and enhance multi-scale feature representation. (2) The Channel Prior Convolutional Attention (CPCA) mechanism incorporates symmetrical operations—using average-max pooling pairs in channel attention and multi-scale convolutional kernels in spatial attention—to automatically learn to prioritize semantically salient regions through channel-wise feature recalibration, thereby enabling balanced feature representation. Coupled with InnerShape-IoU for refined bounding box regression, WCC-YOLO achieves a 4.5% improvement in mAP@0.5:0.95 and a 5.7% gain in mAP@0.5 compared to the baseline YOLOv11n while simultaneously reducing the number of parameters and maintaining near-identical inference latency (δ < 0.1 ms). This work demonstrates the value of explicit symmetry-aware modeling for sports analytics. Full article

Background/Objectives: The post-COVID-19 condition frequently includes dysphonia. We aimed to assess objective and subjective voice disorders and short-term responses to multimodal therapy in patients with isolated post-COVID-19 dysphonia. Methods: This retrospective, single-center pre–post study screened 244 post-COVID-19 patients; a subset of 14 with isolated dysphonia underwent standardized assessment at baseline and at 1-month follow-up. Patient-reported outcomes (Voice Handicap Index, VHI; Voice-Related Quality of Life, V-RQOL) and endoscopic evaluation were performed using videolaryngostroboscopy (LVS) and high-speed videoendoscopy (HSV) with kymographic analysis to quantify parameters describing vocal fold oscillations. The treatment included short-term systemic corticosteroids, inhaled corticosteroids, hyaluronic-acid inhalations, and structured voice therapy. Results: At baseline, HSV revealed signs of glottal insufficiency—irregular and asymmetric vocal fold motion, reduced amplitude and pliability, a disrupted mucosal wave, and an increased open quotient. At follow-up, HSV showed increased oscillation, amplitude, and cycle regularity with reduced left–right asymmetry and phase differences; phonovibrograms displayed clearer and more structured patterns. Perturbation indices decreased across jitter and shimmer measures, and the mean fundamental frequency was lower. Improvements in instrumental measures aligned with better VHI and V-RQOL scores. Conclusions: In patients with persistent dysphonia after acute SARS-CoV-2 infection, comprehensive ENT evaluation with instrumental laryngeal assessment is warranted. Short-term multimodal management was associated with improvements in both HSV-derived measures and patient-reported outcomes; confirmation in controlled studies is needed. Full article

In multi-agent systems (MAS), autonomy is a fundamental characteristic that enables agents to operate independently and adaptively within complex environments. However, such characteristics may cause the system to fall into undesirable situations. On the one hand, purely autonomous agents are difficult to predict. On the other hand, fully controlled agents lose many of their abilities. Therefore, control frameworks have been designed in the form of organizational architectures to help address the need for balance between purely autonomous and fully controlled agents. This paper investigates the impact of organization on the autonomy of the agents. To measure this impact, we propose a set of seven metrics (Behavioral Wealth (BW), Service Wealth (SW), Frequency of Service Searches per Time (FoSST), Frequency of Service Searches per Behavior (FoSSB), Number of Service Searches (NoSS), Number of Service Demands per Behavior (NoSDB), and Number of Provided Services per Demand (NoPSD)) and apply them to a case study implemented in two configurations: with and without organizational aspects. To model organizational aspects, we adopt the Agent–Group–Role (AGR) model, chosen for its structured approach to defining agent responsibilities and interactions. The findings of this study show that the organizational aspects reduce the communication load and enhance the effectiveness of agents. Full article