Search Results (139)

Weak alternating electric fields are widely used in neuromodulation techniques such as transcranial alternating current stimulation (tACS), yet the precise biophysical mechanisms underlying neuronal responses remain incompletely understood. Current computational models often neglect the electrical properties of the extracellular microenvironment, limiting their predictive accuracy. Motivated by experimentally observed frequency-dependent modulation of neuronal activity, we developed a two-compartment model of hippocampal CA3 pyramidal neurons in which extracellular resistance is explicitly parameterized and systematically examined as a key factor influencing neuronal response properties under external electric fields. Within a dual-compartment Hodgkin–Huxley framework, the neuron is divided into a “soma–basal dendrite unit” and an “apical dendrite unit,” accounting for voltage polarization induced by external fields. Using phase-locking ratio curves and three-dimensional parameter response surface, we systematically characterized neuronal sensitivity to field parameters and examined how potassium equilibrium potential ($V_K$) and extracellular resistance ($R_{\mathrm{out}}$) modulate these responses. Our results demonstrate that increasing $R_{\mathrm{out}}$ enhances neuronal responsiveness to external fields, while $V_K$ variations primarily regulate intrinsic excitability. These findings provide mechanistic insights into the frequency-dependent modulation of neuronal responses under weak electric fields, consistent with phenomena observed in biological neural systems, and provide a mechanistic and theoretical framework for understanding the joint effects of electric field amplitude and frequency on neuronal sensitivity to weak electric fields, which may help inform future neuromodulation strategies. Full article

Soliton molecules offer practical advantages in high-speed optical communication, precision spectroscopy, and micromachining. In all-normal dispersion fiber lasers, group velocity dispersion broadens the pulse duration, hindering the attainment of the nonlinearity dispersion balance essential for soliton molecule formation. Consequently, the generation of soliton molecules in such lasers is a technically demanding task. Here, we report an all-normal dispersion fiber laser, mode-locked via nonlinear polarization evolution (NPE) and Lyot filtering. By adjusting the intracavity polarization, this setup allows direct control over pulse interactions, enabling the generation of stable soliton molecules, soliton bound states, and multipulse states. A spectral modulation period of up to 0.95 nm is achieved. In addition, different types of solitons, such as soliton singlets and soliton molecules in tightly and loosely bound states, are observed. Full article

Online ride-hailing platforms increasingly rely on differentiated incentive mechanisms to regulate driver participation and balance supply and demand. However, drivers’ adaptive responses to such incentives introduce dynamic feedback and uncertainty that static equilibrium models fail to capture. This study develops a dual-layer Stackelberg–evolutionary game framework in which the platform acts as a strategic leader setting the order allocation rates and prices, while heterogeneous drivers adapt their working-hour strategies through evolutionary dynamics. Using operational data from Ningbo, China, we calibrated the demand elasticity and driver cost parameters and identified endogenous fatigue-cost thresholds that govern regime shifts in strategy dominance. Simulation results show that uniform incentives tend to drive the system toward single-strategy lock-in, whereas differentiated order allocation and pricing effectively sustain multi-strategy coexistence and mitigate extreme supply polarization. The findings reveal how platform-led differentiation reshapes the evolutionary fitness landscape of drivers, providing actionable guidance for incentive design aimed at stabilizing supply structures, improving platform revenue, and protecting driver welfare. Full article

Background: In multicultural healthcare systems such as the Italian one, migrant children may experience dental care as particularly stressful because linguistic and cultural barriers can limit communication, emotional expression, and understanding of the clinical setting. Aim: Understanding the emotional experience of migrant children during dental visits is essential for improving clinical management in pediatric dentistry and orthodontics within multicultural contexts. Because linguistic barriers often limit verbal communication, this study aimed to explore children’s mental representations, emotional states, and perceptions of the dental environment through drawing and to evaluate the clinical implications for communication and therapeutic collaboration. Methods: This qualitative study was conducted in Italy between 2016 and 2025 and analyzed 50 drawings produced by 50 foreign-born migrant children aged 6–13 years, recruited through an educational cooperative in Piacenza. Most participants originated from developing countries and had limited proficiency in Italian, frequently showing a marked “experience gap” in drawing ability that interfered with normative developmental stages described by Lowenfeld. The analysis focused on spatial organization, line quality, color use, posture, interpersonal distance, and representation of the clinical environment, integrating graphic competence assessment with emotional interpretation. Results: Younger children commonly depicted rigid lines, essential settings, and oversized dental unit lamps, whereas older children increasingly represented threatening or disproportionate instruments, aggressive dentists, and omission of the patient figure. Around age 10, drawings became more detailed and colorful, although symbols of closure, such as locked doors, persisted. In adolescents, representations polarized between rich, coherent scenes and extremely essential drawings dominated by fear, rigidity, minimal environments, and symbols of constraint. The findings suggest that drawing may represent a valuable non-verbal clinical and communicative resource for exploring migrant children’s emotional experience of dental care and for identifying signs of anxiety and vulnerability that may not emerge through verbal interaction alone. Conclusions: These findings support the value of a culturally sensitive dental approach integrating drawing, visual aids, multilingual educational materials, and play-based strategies to reduce communication barriers and improve cooperation in migrant children receiving pediatric dental and orthodontic care. Full article

A multi-dimensional quantitative assessment of high-quality development (HQD) in China’s livestock industry and the identification of its main constraints are essential to understanding its current stage and future direction. Guided by global sustainability targets and the United Nations’ Sustainable Development Goals (SDGs), an evaluation system was constructed by this study. This system integrates five key aspects: product safety, output efficiency, resource conservation, environmental friendliness, and regulatory effectiveness. Using provincial panel data from China for 2013–2022, this research applies the entropy-weighted TOPSIS method, kernel density estimation (KDE), and an obstacle degree model for analysis, the goal is to support food security and foster environmentally sustainable growth. The findings indicate the following: (1) Notable inter-provincial disparities exist in the HQD of China’s livestock industry, revealing a spatial pattern of “leading in the east, stable in the center, and lagging in the west.” (2) The nationwide evolution exhibits a “convergence followed by divergence” pattern: from 2013 to 2017, the primary peak of the KDE rose and its width narrowed; from 2018 to 2022, the primary peak declined and its width widened, indicating that inter-provincial disparities first narrowed and then expanded. At the regional level, the development pattern is characterized by eastern polarization, central stability, and western lock-in. (3) Obstacle factor analysis identifies product safety and environmental friendliness as the principal constraints on HQD in the livestock industry. Addressing these bottlenecks is crucial for ensuring the supply of livestock products (SDG 2: Zero Hunger), promoting resource conservation and green production (SDG 12: Responsible Consumption and Production), and alleviating the ecological and environmental pressures of the livestock industry (SDG 15: Protection of Terrestrial Ecosystems). The challenges related to resources, the environment, and quality safety confronting China’s livestock industry are common among developing countries. Consequently, the evaluation framework established in this study can offer methodological references for relevant nations. Full article

We demonstrate an all-polarization-maintaining (PM) mode-locked thulium-doped fiber laser operating in the net-normal-dispersion regime based on a figure-9 nonlinear amplifying loop mirror (NALM) configuration. A chirped fiber Bragg grating (CFBG) and a commercial PM dispersion-compensating fiber (PM-DCF) are incorporated into the figure-9 cavity, providing a large normal net dispersion and enabling stable dissipative-soliton mode-locking. Under stable dissipative-soliton operation, the laser delivers a maximum output power of 53.6 mW at a repetition rate of 12.31 MHz, corresponding to a pulse energy of 4.3 nJ. The output spectrum has a central wavelength of ~1952 nm with a 3 dB bandwidth of ~11 nm. The all-PM laser oscillator directly generates a fs pulse without extra-cavity compression, achieving a pulse duration of 545 fs at the CFBG arm. Moreover, stable fundamental mode-locking is verified by a high radio-frequency signal-to-noise ratio (SNR) exceeding 82 dB and a long-term root-mean-square (RMS) power fluctuation of 0.45% over two hours. To the best of our knowledge, this represents the highest output power generated from an all-PM-fiber figure-9 laser oscillator in the 2 μm band, alongside fs-pulse operation. This high-power, compact, stable and environment-insensitive fs-pulsed laser source shows great potential as an ideal seed for biomedical imaging and mid-infrared frequency combs. Full article

We have demonstrated a high-power, polarization-maintaining all-fiber amplifier operating at a repetition rate of 1 MHz. The seed laser is a Semiconductor Saturable Absorber Mirror (SESAM) mode-locked oscillator with an 18.1 nm full width in half-maximum (FWHM) spectrum. The pulse duration is stretched to 1.1 ns using temperature-controlled chirped fiber Bragg gratings (TCFBGs) and subsequently amplified in a 40 µm core Yb-doped fiber, achieving a maximum output power of 37 W. The amplified laser exhibits excellent beam quality with an M² factor of 1.04. The pulse duration is compressed to 207 fs in a single-grating compressor with 86% efficiency, yielding an average power of 32 W, a pulse energy of 32 µJ, and a peak power of 154.6 MW. This high-power all-fiber femtosecond laser is a promising source for scientific and industrial applications. Full article

China’s rapid urbanization has driven a pronounced east–west sustainability schism, where affluent coastal corridors face cumulative pollution pressures, while interior regions grapple with ecological fragility and comparatively weaker governance capacity. To diagnose this divergence, we establish the Environmental Stressor Regulatory Capacity (ESRC) framework, integrating indicators across industrial emissions, resource intensity, economic innovation, and institutional resilience. Leveraging Chinese spatiotemporal data from 283 prefecture-level cities from 2003 to 2021, our multi-method analysis reveals three core findings: Dagum Gini decomposition indicates intensifying interregional inequality. Kernel density estimation identifies four distinct transition archetypes: eastern high-base consolidation, central relay diffusion, western polarization–correction, and northeastern asymmetric revitalization. Crucially, random forest regression highlights the high predictive salience of Regulatory Capacity for ESRC variation. These findings are consistent with institutional asymmetry as the key explanatory factor for why some Western regions remain locked in spatial traps. These results may inform targeted ecological compensation for critical zones to support SDG advancement with regional equity. Full article

This paper proposes a method to generate a low-noise 10.23 MHz time-frequency reference signal based on high-order harmonic locking of the repetition rate (f_r) of an optical frequency comb (OFC). An all-polarization-maintaining (PM) Erbium-doped fiber laser with a 122.76 MHz f_r is constructed using the nonlinear amplifying loop mirror (NALM) principle. By applying a feedback control to the intracavity piezoelectric actuator (PZT) and electro-optic modulator (EOM), the 10th harmonic of f_r is phase-locked to a high-performance rubidium atomic clock (Rb clock), achieving low-noise conversion from the Rb clock to the target signal. Experimental results show that the generated 10.23 MHz signal exhibits residual phase noise of −123.4 dBc/Hz at 1 Hz offset and −158 dBc/Hz at 1 MHz offset, and achieves a residual frequency stability of 3.52 × 10⁻¹³ @ 1 s and 3.65 × 10⁻¹⁵ @ 10,000 s. This harmonic locking scheme validates the advantages of photonic microwave generation in achieving ultra-low phase noise while preserving the long-term stability of atomic clocks, providing a strategic solution for next-generation BeiDou Navigation Satellite System (BDS) time-frequency payloads. Full article

This study establishes a municipal-level evaluation system for rural revitalization in China, grounded in the five-sphere integrated framework encompassing “prosperous industries, livable ecology, civilized rural customs, effective governance, and affluent life.” Employing methodologies including the entropy weight-coupling coordination model, LISA spatiotemporal analysis, and multi-scale geographically weighted regression (MGWR), it empirically investigates the evolution and driving mechanisms of rural revitalization development across 282 prefecture-level cities from 2011 to 2023. The findings reveal: (1) Nationwide and regional rural revitalization levels demonstrate a consistent upward trajectory, progressing from a state of “Mild Disorder” to being “On the Verge of Disorder,” with a distinct gradient pattern of “Eastern Region > National Average > Central Region > Western Region.” (2) Significant global spatial correlation is observed, manifesting as polarization typified by “high–high” and “low–low” agglomeration, alongside notable volatility in Northeast and Southwest China. (3) Influencing factors display marked spatiotemporal heterogeneity. Agricultural production efficiency (North China) and technological innovation (nationwide, except the Yangtze River Delta) significantly foster rural revitalization. Conversely, economic development level (Northeast, Central, and Western China), government intervention (Northeast China), and industrial structure upgrading (Northwest China) exhibit constraining effects. The localized positive impacts of urbanization (border areas of Yunnan, Heilongjiang, Sichuan, Jilin, and Tibet) and opening up (border ports) are increasingly evident. Building on these insights, the study proposes recommendations—such as implementing differentiated regional policies, innovating spatial governance models, and activating multidimensional drivers—to overcome the “low-level lock-in” predicament and advance comprehensive rural revitalization. Furthermore, this paper reveals the patterns of multidimensional system coupling and the spatial heterogeneity of driving mechanisms. These findings provide a reference for deepening the understanding of geographical complexity within global sustainable development theory. Full article

Frequency stability of a 509-nm single-frequency laser, a core component combined with an 852-nm single-frequency laser for two-step cesium Rydberg transitions, is critical for quantum control and metrology precision. Utilizing atomic transition as the absolute reference, we achieved laser frequency locking via modulation-free Rydberg two-color polarization spectroscopy (Rydberg–TCPS) and frequency-modulated Rydberg electromagnetically-induced transparency (Rydberg–EIT) spectroscopy with discrete instruments combination and with Red Pitaya FPGA module. The results show that the Red Pitaya FPGA module matches discrete instruments combination in stability, being more compact and only one-tenth the cost. Rydberg–TCPS scheme avoids modulation-induced noise and linewidth broadening, outperforming Rydberg–EIT scheme. The Red Pitaya FPGA module provides a cost-effective, compact solution for Rydberg research, lowering experimental barriers. Full article

This review describes the immunosuppressive effect of secreted phosphoprotein 1 (SPP1)+ tumor-associated macrophages (TAMs) in coordinating the tumor microenvironment (TME) as a functionally unique myeloid cell subgroup. SPP1+ TAMs transcend the traditional M1/M2 paradigm and represent a group of cells that are widely found in various cancer types. SPP1+ TAMs have the characteristics of high expression of SPP1 and promoting immune escape, matrix remodeling and metastasis. We clarify the dual developmental source of SPP1+ TAMs, and introduce the activation process of SPP1+ TAMs through recruitment, polarization and epigenetic locking. After SPP1+ TAMs are activated, they are strategically enriched in the tumor core and tumor marginal area to play their functions. Functionally, SPP1+ TAMs mainly promote the progression of tumors through three mechanisms: (1) Interacting with cancer-associated fibroblasts (CAFs): constructing an immunoexcluded fibrotic niche; (2) Multiple regulation of immune cells; (3) Promoting tumor metastasis and the construction of pre-metastatic niche (PMN). Overall, this review aims to provide a comprehensive overview of the mechanisms mediated by SPP1+ TAMs in the TME, and emphasize their unique role in cancer progression. At the same time, the treatment strategies targeting them are further explored, highlighting their potential as precise therapeutic targets for tumor treatment. Full article

This work presents, to the best of our knowledge, the first experimental report of an erbium/ytterbium double-clad ring fiber laser based on nonlinear polarization rotation (NPR) operating in a self-starting Q-switched high-order harmonic mode locking noise-like pulse (QHML-NLP) regime. The NPR mechanism relies on an arrangement composed of a beam splitter cube, a half-wave retarder, and a quarter-wave retarder. Through specific adjustments of the wave retarders and pump power, the laser cavity engages the QHML-NLP regime, where mode-locked burst-like pulses containing a significant number of NLPs are modulated by a giant Q-switched envelope. The laser system emits at the 132nd-order harmonic mode locking (HML) frequency, representing the highest order achieved to date in the framework of QHML-NLP. Additional features include a broadband optical spectrum with dual-wavelength emission at 1568.4 nm and 1605.9 nm, and maximum energies of 2.37 µJ for the Q-switched envelope and 200 nJ for the mode-locked burst-like pulse. These detailed experimental results reveal remarkable aspects in the NLP dynamics, contributing to a deeper understanding of their physical mechanisms and highlighting their potential as novel laser sources for micromachining and nonlinear optics. Full article

We experimentally and theoretically demonstrate coexistence of three different wavelength-multiplexed bound dual-frequency pulses in an all-fiber mode-locked fiber laser, effectively achieved by exploiting polarization-dependent loss effects and two uneven gain peaks of Er-doped fiber. With the single wall carbon-nanotube-based intensity modulation, wavelength-multiplexed dual-frequency pulses located at 1531.1 nm and 1556.6 nm are obtained. Changing the polarization rotation angles in the fiber cavity, one of the two asynchronous pulses evolves into a bound state of a doublet, in which the center wavelength of the bound solitons is centered at ~1530 nm or ~1556 nm. The relative phase between the two bound solitons or modulation depth of bound solitons can be switched by a polarization controller. A simulation method based on coupled Ginzburg–Landau equations is provided to characterize the laser physics and understand the mechanism behind the dynamics of tuning between different bound dual-frequency pulses. The proposed fiber laser will provide a potential way to understand multiple soliton dynamics and implementation in optical frequency combs generation. Full article

Multimessenger constraints tightly bound the gravitational-wave speed to be luminal, posing a strong filter for modified gravity. This paper develops a symmetry-selected Palatini framework with torsion in which exact luminality at quadratic order is achieved by construction rather than by parameter tuning. Two ingredients shape the observable sector: (i) a scalar PT projector that keeps scalar densities real and parity-even, and (ii) projective invariance implemented via a non-dynamical Stueckelberg compensator that enters only through its gradient. Under an explicit posture (A1–A6), we establish three structural results: (C1) algebraic uniqueness of torsion to a pure-trace form aligned with the compensator gradient; (C2) bulk equivalence, modulo improvements, among a rank-one determinant route, a closed-metric deformation, and a PT-even CS/Nieh–Yan route; and (C3) a coefficient-locking identity that enforces $K=G$ for tensor modes on admissible domains; hence, $c_T=1$ with two propagating polarizations. Beyond leading order, the framework yields a distinctive, falsifiable next-to-leading correction $\delta c_T^2\left(k\right)=b{k}^2/{\mathrm{\Lambda }}^2$ (for $k\ll \mathrm{\Lambda }$), predicting slope 2 in log–log fits across frequency bands (PTA/LISA/LVK). The analysis is formulated to be reproducible, with a public repository providing figure generators, coefficients, and tests that directly validate (C1)–(C3). Full article