Propagation Properties Research Articles

From Decay of Correlations to Locality and Stability of the Gibbs State

We show that whenever the Gibbs state of a quantum spin system satisfies decay of correlations, then it is stable, in the sense that local perturbations affect the Gibbs state only locally, and it satisfies local indistinguishability, i.e. it exhibits local insensitivity to system size. These implications hold in any dimension, require only locality of the Hamiltonian, and are based on Lieb–Robinson bounds and on a detailed analysis of the locality properties of the quantum belief propagation for Gibbs states. To demonstrate the versatility of our approach, we explicitly apply our results to several physically relevant models in which the decay of correlations is either known to hold or is proved by us. These include Gibbs states of one-dimensional spin chains with polynomially decaying interactions at any temperature, and high-temperature Gibbs states of quantum spin systems with finite-range interactions in any dimension. We also prove exponential decay of correlations above a threshold temperature for Gibbs states of one-dimensional finite spin chains with translation-invariant and exponentially decaying interactions, and then apply our general results.

Symmetry Breaking as a Basis for Characterization of Dielectric Materials

This paper introduces a novel method for measuring the dielectric permittivity of materials within the microwave and millimeter wave frequency ranges. The proposed approach, classified as a guided wave transmission system, employs a periodic transmission line structure characterized by mirror/glide symmetry. The dielectric permittivity is deduced by measuring the transmission properties of such structure when presence of the dielectric material breaks the inherent symmetry of the structure and consequently introduce a stopband in propagation characteristic. To explore the influence of symmetry breaking on propagation properties, an analytical dispersion equation, for both symmetries, is formulated using the Rigorous Coupled Wave Analysis (RCWA) combined with the matrix transverse resonance condition. Based on the analytical equation, an optimization procedure and linearized model for a sensing structure is obtained, specifically for X-band characterization of FR4 substrates. The theoretical results of the model are validated with full wave simulations and experimentally.

Verdazyl radical polymers for advanced organic spintronics

Spin currents have long been suggested as a potential solution to addressing circuit miniaturization challenges in the semiconductor industry. While many semiconducting materials have been extensively explored for spintronic applications, issues regarding device performance, materials stability, and efficient spin current generation at room temperature persist. Nonconjugated paramagnetic radical polymers offer a unique solution to these challenges. Despite the recent observation of organic magnetism and magnetoresistance phenomena in radical polymers, their spin propagation properties have not been thoroughly studied. Here, we show that a nonconjugated radical polymer is an exceptional spin transport medium. It shows large effective spin mixing conductance of 3.2 × 1019 m–2 and a room temperature spin diffusion length of 105 nm. Its temperature-independent spin diffusion length suggests that exchange-mediated transport governs spin transport. The substantial spin mixing conductance is promising, and these results establish the potential of radical polymers in emerging spin-based applications.

Effect of fracture aperture on propagation properties of self-expanding polyurethane grout

Effect of fracture aperture on propagation properties of self-expanding polyurethane grout

A phage amplification-assisted SEA-CRISPR/Cas12a system for viable bacteria detection.

Rapid and accurate detection of viable bacteria is essential for the clinical diagnosis of urinary tract infections (UTIs) and for making effective therapeutic decisions. However, most current molecular diagnostic techniques are unable to differentiate between viable and non-viable bacteria. In this study, we introduce a novel isothermal platform that integrates strand exchange amplification (SEA) with the CRISPR/Cas12a system, thereby enhancing both the sensitivity and specificity of the assay and achieving detection of phage DNA at concentrations as low as 4 × 102 copies per μL. Moreover, the incorporation of phages facilitates the specific recognition of viable bacteria and amplifies the initial signal through the inherent specificity and propagation properties of these phages. By employing the phage-assisted SEA-Cas12a approach, we successfully detected viable bacteria in human urine samples without the necessity of DNA extraction within 3.5 hours, achieving a detection limit of 103 CFU per mL. Considering its speed, accuracy, and independence from specialized equipment, this platform demonstrates significant potential as a robust tool for the rapid detection of various pathogens in resource-limited settings, thereby facilitating timely clinical management of UTI patients.

Transverse deformation waves in the non-isothermal lithosphere‒asthenosphere system

The features of the occurrence and propagation of transverse deformation waves in the elastic lithosphere – viscous asthenosphere system under non-isothermal conditions are studied in the approximation of a thin layer. In this case, the phase transition at the boundary of the layers, due to temperature and pressure disturbances, plays an essential role. The qualitative and quantitative properties of propagation of disturbances of thermomechanical fields have been studied in the long-wave approximation. It is shown that due to the energy supply from the non-isothermal asthenosphere, weakly attenuated wave packets can occur, which spread over thousands of km with a characteristic speed of about 100 km/year. This allows them to be considered as a possible trigger mechanism for the massive emission of methane from frozen sedimentary rocks into the atmosphere.

Evolution of hydraulic property and crack propagation of mine roof strata during bending-splitting deformation

To explore the mechanism of water inrush from the mine roof strata, a series of seepage-acoustic emission (SAE) experiments on red sandstone disc samples were carried out. The effects of the height to diameter ratio (H/D) and pore pressure on the mechanical, hydraulic and crack propagation properties of red sandstones were investigated. Test results show that, the peak load of rock samples declines with the decreasing H/D and increasing pore pressure. The seepage process can be divided into three phases, i.e., lower permeability stage, and permeability fluctuation stage and high permeability stage. The crack propagation mainly appears near and after the peak load. In addition, in the low permeability stage, fluid mainly flows through the pores of rock. With the deformation and crack propagation, the fluid enters the cracks, causing fluctuations in permeability. When penetrating cracks forms, a large amount of fluid passes through the cracks, causing a rapid increase in permeability. In the case of high H/D, the water inrush phenomenon obviously lags behind the rock failure, and this lagging phenomenon becomes more significant as the water pressure decreases. The critical displacement (the displacement corresponding to the time of water inrush) can be used to characterize the risk of water inrush. The lower the H/D, the greater the water pressure and the higher water inrush risk. Therefore, it is necessary to control the distance from the working face to the overburden aquifer and reduce the groundwater pressure, so as to reduce the risk of water inrush from the roof.

Exploring the dynamics of overtaking interactions of electron acoustic solitons in beam-driven unmagnetized plasmas: application in the auroral region

Abstract This study explores the propagation of nonlinear electron acoustic waves (EAWs) in an unmagnetized plasma consisting of dynamical inertial cold electrons, hot electrons following (r, q) distribution, a warm electron beam, and background ions. The fluid equations representing the plasma system are reduced to Kadomtsev–Petviashvili (KP) equation for EAWs by using the reductive perturbation technique. Our findings reveal that several key factors significantly influence the propagation and interaction properties of electron acoustic solitary waves (EASWs). These factors include the spectral indices r and q of the generalized (r, q) distribution, the concentrations of cold, hot, and beam electrons, as well as the temperature ratios among these electron populations. Additionally, we investigate the possible types of overtaking interactions between two Kadomtsev–Petviashvili (KP) solitons. The spatial regime for the interaction of two solitons is found to vary depending on the effect of plasma parameters on a single soliton behavior. This comprehensive analysis provides valuable insights into the complex interactions between EASWs, which are relevant for understanding phenomena in laboratory, space, and astrophysical plasmas.

Dual-function switchable terahertz surface plasmon device driven by a GST metasurface

Surface plasmons (SPs) are one of the most effective information carriers for on-chip systems due to their two-dimensional propagation properties. Benefitting from the highly flexible designability, metasurfaces have emerged as a promising route in realizing SP devices. However, related studies are mainly focused on passive devices. Here, by introducing nonvolatile phase-change material Ge2Sb2Te5 (GST) into the metasurface design, we experimentally demonstrate a dual-function switchable SP device in the terahertz regime. Specifically, the device works as a spin-dependent directional plane-wave SP coupler when GST is in the amorphous state, while it works as a spin-dependent directional SP Fresnel zone plate (FZP) when GST is in the crystalline state. The states of GST are switched back and forth using thermal excitation and nanosecond laser illumination, respectively. Our method is simple and robust, and can find broad applications in on-chip photonic devices.

Ion-acoustic Shock and Solitary Waves in Magnetized Plasma with Cairns-Gurevich Distribution Electrons

Abstract The propagation properties of ion-acoustic solitary and shock waves in the magnetized viscous plasma with nonthermal trapped electrons are investigated. The Cairns-Gurevich distribution as the electron distribution is considered to describe the plasma nonthermality and particle trapping. By adopting the reductive perturbation technique, we derived the nonlinear Schamel-Korteweg–de Vries-Burgers (SKdVB) equation, and then obtained the ion-acoustic shock and solitary wave solutions of the SKdVB equation for different limiting cases. It is found that the impact of nonthermal parameter α, external magnetic field Ω, obliqueness lz, wave speed U0, and the ion kinematic viscosity η0 can significantly change the characteristics of the shock and solitary waves. These results may be useful for better understanding the propagation of nonlinear structures in space and laboratory plasma with nonthermal trapped electrons.

Phenotypic Plasticity, Multiple Paternity, and Shell Shape Divergence Across Lake‐Stream Habitats in a Freshwater Mussel Brood (Pyganodon grandis)

ABSTRACT Hydrodynamic forces and their absence appear to exert differential selection pressure on aquatic biodiversity in lake and stream habitats, creating a tight fit between organismal phenotypes and their environments. Ecophenotypic variants may be the result of genetic differentiation or phenotypic plasticity, where a genotype can produce multiple phenotypes dependent on the environment. Freshwater mussels possess a wide degree of morphological variation that frequently covaries with the environment, making them a good system to understand the mechanisms of ecophenotypic variation across hydrological conditions. We designed a two‐year experiment where individuals from the same Pyganodon grandis maternal brood (half and full siblings) were reared at a controlled site and four natural sites involving one lake and three streams. At the end of the experiment, shell shape was quantified for recaptured (N = 70), wild (N = 206), and zoo‐reared (N = 305) mussels. The maternal individual and 46 recaptured mussels were sequenced for genomic single nucleotide polymorphisms to test for multiple paternity and its effect on offspring morphology. Analysis of covariance found significant differences in shell shape between rearing sites, particularly between stream and lake habitats, but no shape differences were detected across the three stream sites. At two of the four sites, the shell shape of recaptured individuals was not significantly different than that of wild populations. Genomic sequencing and parentage analysis identified 11–27 different fathers among recaptured individuals. Yet no genetic differences were present between stream and lake habitats, and there was no paternal effect on shell shape. Taken together, phenotypic plasticity, over genetic differentiation, is identified as the primary mechanism of ecophenotypic variation. Plasticity is likely ubiquitous across freshwater mussels and may be a key adaptation given their high variance in habitat use. Multiple paternity may also play a role in the evolution of phenotypic plasticity, allowing more males from greater distances opportunities for fertilization, thus increasing genetic connectivity. Lastly, phenotypic plasticity and multiple paternity are convenient properties for freshwater mussel conservation and propagation. Multiple fathers increase the genetic variation of propagated broods, while plasticity may provide resilience to the release of stocked individuals across environmental heterogeneity.

Radially polarized partially coherent beams with prescribed sinh-Gauss non-uniform correlation structure

We introduce a kind of radially polarized partially coherent beam with a prescribed sinh-Gauss non-uniform correlation structure, named a radially polarized sinh-Gauss non-uniformly correlated (RPSNC) beam. Utilizing the ordinary Huygens–Fresnel principle, we derive the analytical formulas for the spectral intensity and the spectral degree of polarization (DOP) in free space and investigate the beam’s propagation properties through numerical simulations. The results demonstrate that RPSNC beams exhibit a self-focusing property during propagation, with the focal position adjustable by varying the coherence length. Additionally, the spectral DOP in the central region forms a distinctive single-ring structure as the beam propagates. These unique properties make RPSNC beams promising for applications in free-space optical communications, beam shaping, and optical trapping.

On the Influence of the Solar Wind on the Propagation of Earth-impacting Coronal Mass Ejections

Coronal mass ejections (CMEs) are subject to changes in their direction of propagation, tilt, and other properties as they interact with the variable solar wind. We investigated the heliospheric propagation of 15 Earth-impacting CMEs observed during 2010 April to 2018 August in the field of view (FOV) of the Heliospheric Imager (HI) on board the STEREO. About half of the 15 events followed self-similar expansion up to 40 R ⊙. The remaining events showed deflection either in latitude, longitude, or a tilt change. Only 2 events showed significant rotation in the HI1 FOV. We also use toroidal and cylindrical flux rope fitting on the in situ observations of interplanetary magnetic field and solar wind parameters to estimate the tilt at L1 for these 2 events. Although the sample size is small, this study suggests that CME rotation is not very common in the heliosphere. We attributed the observed deflections and rotations of CMEs to a combination of factors, including their interaction with the ambient solar wind and the influence of the ambient magnetic field. These findings contribute to our understanding of the complex dynamics involved in CME propagation and highlight the need for comprehensive modeling and observational studies to improve space weather prediction. In particular, HI observations help us to connect observations near the Sun and near the Earth, improving our understanding of how CMEs move through the heliosphere.

Streamer propagation in CO2 and N2/CO2 mixtures at atmospheric pressure

Abstract This study investigated streamer discharge in CO₂ and N2/CO2 mixtures. Experiments were conducted at atmospheric pressure and room temperature conditions by using a point-to-plane electrode configuration. A repetitive pulse discharge at 50 Hz was used to stabilise the discharge in CO₂. Under these conditions, the discharge current and intensified charge-coupled device (ICCD) camera images were systematically analysed during streamer evolution in CO2. The results revealed that streamer propagation and electrical properties were considerably influenced by the N₂ concentration in CO₂. Analysis of the emission of secondary streamers indicated that the emission ratio of primary streamers and secondary streamers in CO2 differed considerably from that in air. The onset delay time of streamer discharge was measured and statistically processed based on previous studies of streamer onset processes. Findings indicated an increase in the discharge delay time and its dispersion when N₂ was added to CO2, which indicated that variations in the initial electron content affected the inception process of streamer discharge.

The Spatiotemporal Structure of Induced Magnetic Fields in Callisto's Plasma Environment Due to Their Propagation With MHD Modes

AbstractWe investigate how the spatiotemporal structure of induced magnetic fields outside of Callisto is affected by their propagation with the magnetohydrodynamic (MHD) modes. At moons that are surrounded by dense magnetized plasmas like the Galilean moons, low‐frequency induced magnetic fields cannot propagate with the ordinary electromagnetic mode as is implicitly used by standard analytical expressions. Instead, the induced magnetic fields propagate with the MHD modes, which exhibit anisotropic propagation properties and have finite velocities. Using an MHD framework, we model the spatiotemporal effects of the transport on the induced signals and analyze their contribution to Galileo's C03 and C09 flyby observations. We find that the induced magnetic field in Callisto's plasma environment is asymmetric with a pronounced upstream/downstream asymmetry. By neglecting the transport effects, the amplitude of the induced magnetic field is under‐ or overestimated by up to tens of percent, respectively. Additionally, we find that MHD wave and convection velocities are strongly reduced in Callisto's local plasma environment, resulting in an additional temporal delay between the emergence of the induced field at the surface of Callisto or the top of its ionosphere and the measurements at spacecraft location. The associated phase shift depends on the location of the observer and can reach values of several to tens of degrees of the phase of the primary inducing frequency. Transport effects impact the observed induction signals and are consistent with the C03 and C09 magnetic field measurements.

Design of a Noise Mitigation System Using Lightweight Graded Micro-Porous Material

Noise is a concern in industries like aviation. Existing acoustic materials have limitations in terms of effective broadband sound attenuation and operating conditions. This work addresses these limitations by designing and developing a noise mitigation system using lightweight graded micro-porous material made from Cenospheres and high-char binder. However, Cenospheres are nearly spherical with rough surfaces, so determining the flow properties of sound propagation is challenging, and direct measurements are expensive. We developed a multivariable-fit inverse method to estimate these properties using an experimental absorption coefficient, validated first with smooth-surface glass beads and then applied to micro-porous material. The determined flow properties were used in a predictive acoustic analysis and validated experimentally. It was demonstrated that a microstructurally graded material is needed to optimize both sound absorption and transmission loss. A graded material system designed for turbofan engine acoustic liners (50 mm thick) met the target broadband sound absorption coefficient of ≥0.50 and transmission loss of ≥20 dB above 500 Hz. The study also highlights that larger particles in thicker layers enhance sound absorption, while a graded micro-structure improves overall acoustic performance. This research offers a novel approach for designing a lightweight acoustic material for aviation, marking a breakthrough in passive noise mitigation technology.

The Support Behavior of the Solution to the Cauchy Problem for Higher Order Weighted Parabolic Equations

In this paper we study the finite speed of propagation property to the Cauchy problem for weighted higher order degenerate parabolic equations. We prove that if initial data is compactly support in some fixed ball, then so does the solution for all time. Because we are considering exponentially growing weights, the size of the support should expand more slowly over time than in the non-weighted case. We prove that for a large time the support of the solution expand with logarithmic rate. That estimate of support meets with known estimate for second order parabolic equations. The main tool of the proof is based on local energy estimates on annuli which allows us to consider even nonpower character of weights. It works even in cases when the weighted Gagliardo-Nirenberg inequality does not occur. Early that approach was utilized by D. Andreucci and by author for equations in domains with noncomact boundaries and for higher order parabolic equations including the thin film equation.

Propagation properties of two types of sinc Schell-model beams in oceanic turbulence

Abstract The evolution of two types of sinc Schell-model (SSM) beams, each considered with both circular and rectangular symmetries, is investigated during their propagation in oceanic turbulence. The expressions for the spectral intensity and spectral coherence of the transmitted optical field are derived using the extended Huygens-Fresnel principle. Based on these expressions, numerical simulations are carried out to explore how source and turbulence parameters influence the transmitted field. The results demonstrate that the spectral intensity distribution of the SSM1 beam evolves from an initial Gaussian profile into a circular or rectangular flat-topped shape during propagation, while the SSM2 beam develops into a ring-shaped or array-like pattern. As the dissipation rate of turbulent kinetic energy decreases, or the mean square temperature dissipation rate and the strength of temperature and salinity fluctuations increase, the energy of these beams disperses from its concentrated regions to the surrounding areas, causing the characteristic intensity distributions to become blurred. Additionally, the coherence of these beams exhibits oscillatory distributions, with the SSM2 beam showing stronger oscillations compared to the SSM1 beam and displaying greater sensitivity to changes in turbulence parameters. The intensity and coherence distributions are also affected by source parameters, which play a dominant role at shorter propagation distances. However, as the distance increases, turbulence parameters gradually become the primary influence. The results presented here may be applied to oceanic optical communication and remote sensing.

Optical skyrmions and tunable fine spin structures in deep-subwavelength scale at metal/graded index material interfaces

A skyrmion is a topological quasiparticle that has been studied widely in nuclear physics, condensed matter physics, cosmology, and optics. Previously, the optical skyrmions in the surface plasmon polaritons platform were not tunable because the dielectric properties of the material were fixed. In the study, we introduce the graded refractive index materials into the near-field optical system and systematically investigate the propagation properties, dispersion relations, and spin-orbit decomposition of the surface waves at the metal/graded refractive index materials interface. Our theoretical results exhibit that the topological spin skyrmions can be formed in the system and the dimensions of optical skyrmions can be tuned by varying the central permittivity and exponent of the graded refractive index materials. Additionally, the spin fine structure, in which the spin state varies sharply from the ‘up’ state to the ‘down’ state, can be also controlled by adjusting the materials properties of the graded refractive index materials. The minimal full width of the spin fine structure is 0.254λ, which has the potential for achieving the displacement metrology with a sensitivity of 2.54 × 10−7λ theoretically. Our findings provide an extra degree of freedom to control the formation and scale of fine spin structures in optical skyrmions and open an avenue for next-generation pico-photonics.

Modelling the effective sound propagation properties of a hexagonal acoustic metamaterial using a dissipative equivalent-fluid approach under different termination conditions

This paper presents a theoretical approach to assess the effective sound propagation properties of an acoustic system comprising multiple subwavelength resonators under grazing incidence. Consequently, the high capacity required to handle sound transmission, absorption and reflection are theoretically and experimentally reported. Viscothermal effects are considered by employing the dissipative equivalent-fluid approach and the respective analytical estimations of transport parameters provide accuracy in describing the resistive and reactive phenomena in the acoustic field for different termination conditions. The dissipative equivalent-fluid approach proposed here is contrasted with other well-established methods and numerical computing. The results evidence good agreement even when multiple resonances are associated, enabling the implementation of single, dual and triple resonance systems. The results of this work present a validated simplified approach that provides analytical derivations of the effective sound propagation properties in a complex association of side-branches Helmholtz resonators.