Spreading dynamics of an SVIRS model.

Optical vortices are beams with spiral phase wave fronts capable of carrying different topological charges. This paper presents the expression for Gaussian vortex light and simulates vortices with topological charges of 0, 1, and 2, revealing a “hollow” extinction phenomenon. We derive the relationship between the radius of Gaussian vortex beams and their topological charges, express the extinction ratio of hollow vortices, and calculate the beam radius. The study demonstrates a linear relationship between the extinction ratio and topological charge (from 1 to 20). The fitting accuracy between the simulated hollow radius and the Gaussian vortex approximated radius reaches 85.93%, with an error margin of 17%. In laboratory experiments using a liquid crystal spatial light modulator, we constructed a vortex light system employing a 532.0 nm laser to generate 10 interference fringes of hollow vortex light with topological charges ranging from 10 to 100 on a CCD detector. Pixel measurements were taken for both inner and outer radii corresponding to these charge patterns, enabling precise calculation of extinction ratio. The experimental results show a similar trend to the theoretical predictions, demonstrating that hollow vortex light with extinction properties holds potential applications in signal encryption.

Abstract Precise alignment sensing and control are essential for maintaining the stability of laser interferometric gravitational-wave detectors. Conventional Wave Front Sensing technique (WFS), which relies on the beat between the carrier and phase-modulated (PM) sidebands, is dominated by arm-axis signals when the carrier resonates in the full interferometer. This dominance limits the detection of other optical axes, such as the Power Recycling Cavity (PRC) and incident beam axes. To address this problem, we propose a novel sensing technique, ‟Phase-Modulated-sideband × Phase-Modulated-sideband Wave Front Sensing„ (PMPMWFS), which demodulates the beat signal at the difference frequency between two anti-resonant PM sidebands. We derived the theoretical response of PMPMWFS and experimentally demonstrated it using the Power-Recycled X-arm (PRXARM) configuration of KAGRA. The results show that PMPMWFS effectively decouples angular fluctuation signals of the PRC and incident beam from those of the arm cavity and provides orthogonal signal components for the end mirror of the arm cavity. Furthermore, feedback control using PMPMWFS achieved stable interferometer locking for over one hour. These results demonstrate that PMPMWFS offers an effective sensing method for decoupling multiple alignment degrees of freedom in future gravitational-wave detectors.

The effect of fiber additives (basalt and polypropylene) on the process of nitriding by self-propagating high-temperature synthesis (SHS) of a powder mixture consisting of silicon, aluminum and microsilica was investigated. The effect of fiber additives on the combustion wave front propagation rate and the maximum combustion temperature, as well as on the nitrogen content, phase composition and structure of combustion products was studied. Optimum fiber additives suitable for use as reinforcing components of β-SiAlON obtained by the SHS method were determined. Ill. 4. Ref. 14. Tab. 1.

On the analytic-Gevrey wave front set with respect to iterates of a class of Hörmander’s operators near points with parabolic degeneracy

ABSTRACT The estimation of cloud water/ice content and precipitation intensity using radar is based on the principle of incoherent back-scattering from water droplets or ice particles constituting these meteorological objects. Accordingly, this mechanism assumes uniform particle distribution in the radar volume. However, extant literature offers substantial evidence that the uniform distribution of droplets in clouds and rain is predominantly unique rather than general to all cases. This study utilized a slice approach to evaluate the contribution of medium-scale fluctuations in particle concentration (clustering) commensurate with the size of the radar volume when estimating the radar cross-section (RCS) of clouds and rain. This approach considers coherent scattering from particles located near the electromagnetic wave front (in slices) and demonstrates that incoherent scattering occurs exclusively when the Poisson Index (P.I.), defined as the ratio of the variance to the average number of particles in the slices, is equivalent to 1. The use of the slice approach facilitated the parameterization of the contribution to back-scattering of the heterogeneity of the concentration of cloud and rain droplets and the deviation of its fluctuations from Poisson’s law on the scale of the radar volume through the P.I. value. A computer simulation was conducted to ascertain the P.I. of particle number fluctuations within a radar volume containing particle clusters. Clustering was found to lead to deviations in the P.I. index from 1. The corresponding calculated biases in reflectivity estimates were similar to those observed using the incoherent approach. The primary parameters of particle concentration in the radar volume and clusters conducive to the deviation of P.I. from 1 were determined.

This research focuses on simulating the free surface flow of multiple fluids within porous structures using the incompressible smoothed particle hydrodynamics (ISPH) method. Understanding fluid dynamics in porous media is crucial in various fields, including environmental engineering, hydrology, geology, and petroleum engineering. The study explores how capillary, viscous, and gravitational forces influence fluid behavior in porous structures, offering insights into phenomena such as capillary rise, fluid distribution, and buoyancy-driven flow. The research details ISPH simulation results, highlighting the effects of parameters like fractional time derivative, density, and porosity on fluid movement and wave front tracking. Furthermore, an artificial neural network (ANN) model is created to predict wave front tracking, demonstrating its precision in estimating wave front values based on the ISPH simulations. The high density ratio between the two fluids effectively enhances their interactions. Additionally, a lower porosity parameter exacerbates the resistance within the porous structure, thereby reducing the interactions and velocity field of the fluids. The fractional time derivative is a useful parameter for accelerating the interaction processes between the two fluids.

The development of dynamic components for controlling wave fronts in the sub-terahertz region of the electromagnetic spectrum has emerged as a frontier research topic for many applications in sensing and communications. One approach which has attracted much attention involves the use of active metasurfaces, tiled arrays of sub-wavelength elements with properties that can be reconfigured via external actuation. In nearly all cases, these metasurfaces are employed as either transmissive or reflective elements, taking advantage of their strong and tunable interaction with free-space electromagnetic waves. These interactions can be significantly enhanced through the use of surface waves propagating parallel to the metasurface array, although very few studies have exploited this option. Here, we integrate a metasurface into the interior of a parallel-plate waveguide in a configuration explicitly designed to exploit this surface-wave geometry. We show that varying the electrical properties of the active metasurface changes the wave vector of the guided mode, and thereby alters the emission angle of radiation out-coupled through a leaky-wave slot aperture. These results, which are consistent with numerical simulations, represent a new approach to broadband beam steering suitable for the sub-terahertz spectral range.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-33364-1.

In the last century, most sensorimotor studies of cortical neurons relied on average firing rates. Rate coding is efficient for fast sensorimotor processing that occurs within a few seconds. Much less is known about long-term working memory with a time scale of hours (Ericsson and Kintsch, 1995). The discovery of the millisecond precision of spike initiation in cortical neurons was unexpected (Mainen and Sejnowski, 1995). Even more striking was the precision of spiking in vivo, in response to rapidly fluctuating sensory inputs, suggesting that neural circuits could, in principle, preserve and manipulate sensory information through spike timing. High temporal resolution enables a broader range of neural codes. It could also support spike-timing-dependent plasticity (STDP), which is triggered by the relative timing of spikes between presynaptic and postsynaptic neurons in the millisecond range. What spike-timing mechanisms could regulate STDP in vivo? Cortical traveling waves have been observed across many frequency bands with high temporal precision. Traveling waves have wave fronts that could link spike timing to STDP. As a wave front passes through a cortical column, excitatory synapses on the dendrites of both pyramidal and basket cells are synchronously stimulated. Inhibitory basket cells form a calyx on pyramidal cell bodies, and inhibitory rebound following a strong transient hyperpolarization can trigger a backpropagating action potential, which arrives shortly after the excitatory inputs on pyramidal dendrites. STDP activated in this way could persist for hours, creating a second-tier network. This temporary network could support long-term working memory, a cognitive network riding above the long-term sensorimotor network. On their own, traveling waves and STDP have not yet yielded new insights into cortical function. Together, they could be responsible for how we think (Sejnowski, 2025).

Abstract The upcoming Roman Coronagraph will be the first high-contrast instrument in space capable of high-order wave front sensing and control technologies, a critical technology demonstration for the proposed Habitable Worlds Observatory (HWO) that aims to directly image and characterize habitable exoEarths. The nominal Roman Coronagraph observing plan involves alternating observations of a science target and a bright, nearby reference star. High contrast is achieved using wave front sensing and control, also known as “digging a dark hole,” where performance depends on the properties of the reference star, requiring V < 3, a resolved stellar diameter <2 mas, and no stellar multiplicity. The imposed brightness and diameter criteria limit the sample of reference star candidates to high-mass main-sequence and post-main-sequence objects, where multiplicity rates are high. A future HWO coronagraph may have similarly restrictive criteria in reference star selection. From an exhaustive literature review of 95 stars, we identify an initial list of 40 primary and 18 reserve reference star candidates relevant to both the Roman Coronagraph and HWO. We present results from an initial survey of these candidates with high-resolution adaptive optics imaging and speckle interferometry and identify no new companions. We discuss the need for higher-contrast observations to sufficiently vet these reference star candidates prior to Roman Coronagraph observations, along with the implications of reference star criteria on observation planning for Roman and HWO.

HighlightsWhat are the main findings?In discontinuously reinforced composites, hollow inclusions enhance stress wave attenuation by over 20% compared to solid ones due to greater deformation and scattering.Elongated inclusion orientation strongly affects attenuation, with perpendicular alignment increasing efficiency by 18.5%.A compliant interlayer and specified inclusion distribution further improve attenuation by 3–11%.What is the implication of the main finding?Optimizing inclusion shape and orientation enhances stress wave attenuation.Hollow inclusions and compliant large interlayers increases energy dissipation and scattering.Controlled inclusion distribution enables efficient stress wave barrier zones design.This study investigates the design factors of stress wave barrier zones intended for manufacturing machines under impulse loading, using polymer discontinuously reinforced composites with specified internal microstructures, which effectively suppress stress at the wave front, promote uniform stress distribution, improve impact resistance, and reduce vibrations and noise. Two-dimensional representative unit cells and explicit finite element simulations were used to analyze stress wave propagation under impulse loading. The effects of inclusion shape, orientation, distribution, interlayer, and size of the interface on stress wave scattering and attenuation were examined. In our models, hollow inclusions demonstrated 20.6% higher attenuation compared to solid inclusions, with the hollow fiber inclusion showing the most significant improvement. Inclusion orientation relative to the stress wave direction affected attenuation by 18.5%, while redistribution of inclusions and addition of a compliant interlayer contributed additional increments of 3–11%. These results highlight the critical role of microscale topology in stress barrier zone designing, such that the combined adjustment of inclusion shape, orientation, interlayer presence, and spatial distribution provides an effective strategy to maximize stress wave attenuation.

The paper presents the model, methodology and results of experimental research focused on identification of the wave form generated during the crossing of 30-ton and 60-ton vehicles on a ribbon-type pontoon bridge and the analysis of its influence on the characteristics of the maximum draught. A review of the literature revealed that ribbon-type pontoon bridges are subject to significant vertical deflection. This results from the need to generate sufficient buoyant force to balance the weight of crossing vehicles. The area of maximum draught occurs directly beneath the vehicle and moves along with it, generating a front wave—referred to as a bow wave—which propagates along the crossing and alters the local draught of individual pontoons. Due to the fact that pontoon bridges transfer loads through buoyancy force, a key issue in the process of their design is the precise knowledge of the formation of the volume of the droughted part. No information was found in any publication about the influence of the front wave on the draught form of a ribbon-type pontoon bridge. Their authors do not indicate that the analytical or simulation models they use reflect this phenomenon. Equally, the analysis of the methodologies and results of experimental studies in this area did not show that any attempts were made to identify the form of the front wave. The paper presents the results of measurements of vertical displacements of individual pontoon blocks of the crossing and the characteristics of the front wave occurring during the passing of 30- and 60-ton vehicles with speeds ranging from 7.4 to 30 km/h. Based on the obtained data, an attempt was made to identify the phenomenon of undulation of the surface of the water obstacle and its impact on the loads on the bridge structure. The results allow for identifying a significant front wave with a wavelength of 30–50 m, appearing clearly at speeds above 21 km/h. This wave substantially affects the draught measurement—at a speed of 25 km/h, the maximum draught increased by approximately 30%. Statistical analysis confirmed the significance of this effect (p < 0.05), indicating that wave formation must be considered for accurate determination of pontoon block draught. Furthermore, the mass of the vehicle had a strong influence on the wave and draught parameters—the 60-ton vehicle produced wave troughs and draught depths 55–65% greater than those of the 30-ton vehicle.

Many complex systems with societal relevance are excitable, including brain tissue, cardiac tissue, heat waves, and epidemic spread. In cardiac tissue, arrhythmias often arise when electrical conduction is blocked by incomplete recovery after a previous stimulation. We recently presented a topological theory for excitable media that also captures conduction blocks. Therein, points where a wave front or a wave back spatially connects to a conduction block were shown to be topologically preserved, and denoted heads and tails, respectively. Here, we introduce algorithms to automatically localize heads and tails in excitation patterns on triangle meshes. We describe two variants, depending on the co-dimension of the forbidden zone in state space. As a result, the conduction block region is rendered either as a line of conduction block or an extended conduction block region. A key operation is to apply a bitwise OR operation onto states of a local vertex according to a partitioning into forbidden zone (Z), excited (E), unexcited (U), and their respective signed variants (S), which we abbreviate as ZEUS methods. The methods are applied to visualize heads, tails, and conduction blocks in simulated data and optical voltage mapping recordings of ventricular tachycardia in rabbit hearts. We compare the outcome to classical phase singularity analysis. Theoretical relations between the different options and advantages of each method are discussed. Robust algorithms are presented and made publicly available to identify certain topologically preserved points in excitation patterns. These methods can be used for automated analysis and classification.

This study investigates tip leakage flows resulting from the gap at the tip of turbine's blades, focusing on the flow dynamics under pulsed conditions. Wall-resolved large-eddy simulations are performed using the in-house solver IC3 for two gap heights, h/c=0.94% and h/c=2.18%. After validating the upstream turbulent boundary layer, an in-depth analysis of the tip leakage flow is conducted during the initial regime, i.e., before the passage of the unsteady shock wave front. Classical vortices—tip leakage vortex (TLV), induced vortex (IV), and tip separation vortex (TSV)—are identified. Results align with the literature for subsonic flows, showing that TLV intensity and trajectory depend on h/c. Power spectral density and spectral proper orthogonal decomposition analyses confirm the lack of vortex coherence. Barycentric turbulence maps reveal strong turbulence anisotropy, particularly in the tip region. The originality of this paper lies in its second part. For the first time, LES of tip gap flows submitted to an unsteady shock wave front are conducted. Two shock intensities defined by their pressure jump Π=1.6 and Π=3.0 are considered. For Π=1.6, variations in h/c do not significantly affect lift, but vorticity generated in the tip gap amplifies TLV, IV, and TSV circulations. At Π=3.0, stronger shock–wave interactions may be source of high losses due to an attached trailing-edge shock, boundary layer separation, and intensified pitchwise and spanwise vortices motions. These findings highlight the complexity of tip leakage flows under unsteady shock interactions and provide new insights into their aerodynamics.

Abstract Coronal mass ejections are known drivers of large-scale waves in the low corona. However, wave dynamics in the extended corona and inner heliosphere remain largely unexplored. Here, we report the first observational and numerical evidence of coherent global compressive oscillations in the outer corona and inner heliosphere, revealed by white-light Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph (LASCO) C3 data and an MHD simulation. Analyzing the coronal mass ejection event of 2012 July 23 using spectral proper orthogonal decomposition, we isolate two distinct wave signatures: (1) a directional fast-mode shock-like compressive wave that dissipates completely within 3 hr, and (2) a large-scale global circular wave front consistent with fast-mode MHD behavior, lasting 7 hr and extending across the LASCO C3 field of view, marking the first detection of such a global oscillation. Our findings reveal a previously unrecognized component of coronal mass ejection–driven wave activity, providing new constraints on the dynamics of the extended corona and inner heliosphere.

Abstract Background Prolonged myocardial ischemia triggers a ’wave front’ of cardiomyocyte death due to oxygen and nutrient deprivation. Thus, timely reperfusion and salvage of ischemic myocardium are the primary objectives of revascularization therapies for patients with flow-limiting coronary artery disease. However, despite its well-established benefits, evidence suggests that reperfusion itself can inflict additional injury to the affected myocardium, which remains a significant concern. Purpose This study aimed to explore the early transcriptomic responses to reperfusion in the myocardium of patients undergoing coronary artery bypass grafting (CABG) surgery. Methods Eleven male patients with NSTE-ACS and significant stenosis (>90%) of the left anterior descending (LAD) artery, with an ejection fraction (EF) greater than 40%, were included. During the CABG surgery, myocardial biopsies were collected from the anteroseptal region of the left ventricle at two timepoints: before and five minutes after graft placement (reperfusion). Total RNA was isolated from the cardiac tissue, and RNA libraries were prepared using the NEB Next Ultra kit and sequenced on an Illumina Novaseq platform. Low-quality reads were filtered and mapped to GRCh38 with HISAT2. Transcripts were assembled with StringTie, and read counts were normalized to FPKM. Differential expression analysis (reperfusion vs. ischemia) was performed with DESeq2 (log2FC ≥ ±1, p-adj ≤ 0.05). Protein-coding genes underwent GSEA using GenePattern with MSigDB signatures. Results A paired-sample comparison identified 214 differentially expressed protein-coding genes (DEGs) - 177 significantly downregulated and 37 upregulated during reperfusion (Figure 1A). Of these, 14 DEGs met the criterion ofp-adj < 0.05 (Table 1). The most upregulated were the transcripts of early response genes Fos and FosB (FosB Proto-Oncogene, AP-1 Transcription Factor Subunit). The most downregulated DEG was endothelial cell-specific molecule 1 (ESM1; log2FC = -1.94), a pro-inflammatory factor involved in angiogenesis and secreted by inflamed endothelium. Downstream enrichment KEGG and GO analyses revealed reperfusion-induced upregulation of genes related to mitochondrial ATP production, cardiac contraction, and antioxidant activity (GO Molecular Function Antioxidant activity; NES=1.91, p-adj=0.019). Conversely, genes associated with cellular and nuclear division, inflammation, the p53 mediated apoptotic pathway, and cellular response to glucose starvation were downregulated (Figure 1B and C). Conclusions Reperfusion led to beneficial transcriptomic changes, upregulating mitochondrial energy production, contractile and antioxidant mechanisms, while downregulating pro-inflammatory, pro-fibrotic, and pro-apoptotic pathways. These findings highlight the predominantly positive transcriptomic responses that drive myocardial recovery following revascularization.Figure 1. Table 1.

Abstract Two linearly independent vector solutions to the electromagnetic equations in free space are obtained from the Heaviside electric and magnetic fields exchange symmetry. The general solution is described by a linear combination of the two polarizations with complex coefficients, E = a 1 E ℘ 1 + a 2 E ℘ 2 . The Poynting energy flux and density described in terms of these polarizations, distinguish an intensity contribution not involving the fields’ gyration and a contribution dependent on the gyration (spin) coefficient σ. The Poynting S = ε μ [ Re ( E ℘ 1 × E ℘ 2 ∗ ) + 1 2 i σ ( E ℘ 1 × E ℘ 1 ∗ + E ℘ 2 × E ℘ 2 ∗ ) ] decomposition is quite general, valid in the non paraxial and paraxial regimes. An entirely classical characterization of the fields intrinsic rotation is established (counterpart to quantum spin) as an ancillary result. For monochromatic fields, vector solutions in any orthogonal coordinate system are established. Within this context, the orthogonality conditions between a vector function F and its curl ∇ × F , are obtained in the main proposition. The orthogonal vector solutions separate the explicit solutions in the intensity and gyration aforementioned parts. If there is a wave front structure and an elliptical polarization, there is an additional contribution to the energy flow and density not present in plane waves. The energy decomposition of circular cylindrical and plane waves are evaluated to exhibit some of these novel features that only appear in structured waves. The present approach makes no reference to angular momentum, neither orbital nor spin. Surprisingly, this separation differs from the accepted Poynting breakup in orbital and spin components, even in the paraxial approximation.

Proper curvature collineations (CCs) of plane fronted gravitational waves (GWs) in f(R) gravity are addressed in this paper. We first think about vacuum classes of plane GWs and analyze their CCs using mathematical and integration methods, and we also use a 6×6 Riemann curvature matrix. This sorting results in ten cases: three where the spacetimes turn conformally flat and generate infinite-dimensional vector spaces (IDVs), and seven where CCs form IDVs.

Abstract The major earthquake sequence that struck near the South Sandwich Islands in the Antarctic sector of the Atlantic Ocean on August 12, 2021, began with a magnitude M w 7.5 rupture at 18:33 UTC, followed by a more intense M w 8.1–8.3 mainshock three minutes later. The tsunami generated by this complex event spread throughout the World Ocean, where, in the northeast Pacific Ocean, it was observed in such distal regions as California, British Columbia and the Aleutian Islands, 15,000–18,000 km from the source area. Tsunami waves recorded by multiple oceanic sensors show that the tsunami arrived at the coast of Vancouver Island about 23 h after the earthquake and then two hours later at coastal Alaska and the Aleutian Islands. The 10–20 min period waves that dominated both the coastal and open-ocean tsunami waveforms appear to be tightly associated with the source properties. A numerical model developed for the event closely reproduces the open-ocean records. To achieve this close agreement between the observed and modelled tsunami waveforms in deep water, we adjusted the model to account for the dispersion that occurred during propagation of the waves across the Pacific Ocean. Our findings further show that kinematic models commonly used for tsunami warnings (and based solely on “dead-reckoning” estimates of wave front trajectories) give for far-field events earlier estimated arrival times (ETAs) than the measurable arrival times (TAs) of the tsunami waves.

The criteria for optimizing shock-wave modes to increase the fatigue life of aircraft engine alloys are discussed with reference to laser shock peening (LSP). They are based on the self-similarity of plastic wave fronts and the kinetics of fatigue cracks related to the Swegle-Grady power law of structured plastic wave fronts and the Paris power law of fatigue crack advance. It is shown that the self-similar patterns and the power-law relationships of structured wave fronts at shock pulse amplitudes of 1-10 GPa and strain rates of 105-109 s-1 correspond to “action invariants” that determine the dissipative properties (stored energy) of materials caused by multiscale defect development. The relationship between the “action invariants” of structured plastic waves, the fatigue crack kinetics and the structural scaling invariants is shown using the 3D data of qualitative fracture surface profilometry. The methodological principles for studying material behavior under successive shock-wave and fatigue loads have been developed to optimize LSP processes and thus to ensure maximum fatigue life.