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Abstract \nSpectroscopic techniques coupled with chemometric approaches have been widely used for quality evaluation of agricultural and food (agri-food) products due to the nondestructive, simple, fast, and easy characters. However, these techniques face the issues or challenges of relatively weak robustness, generalizability, and applicability in modeling and prediction because they measure the aggregate amount of light interaction with tissues, resulting in the combined effect of absorption and scattering of photons. Optical property measurement could separate absorption from scattering, providing new insights into more reliable prediction performance in quality evaluation, which is attracting increasing attention. In this review, a brief overview of the currently popular measurement techniques, in terms of light transfer principles and data analysis algorithms, is first presented. Then, the emphases are put on the recent advances of these techniques for measuring optical properties of agri-food products since 2000. Corresponding applications on qualitative and quantitative analyses of quality evaluation, as well as light transfer simulations within tissues, were reviewed. Furthermore, the leading groups working on optical property measurement worldwide are highlighted, which is the first summary to the best of our knowledge. Finally, challenges for optical property measurement are discussed, and some viewpoints on future research directions are also given.Emerging techniques for measuring optical properties are briefly introducedQualitative analyses of maturity evaluation and defect detection are reviewedQuantitative analyses of attribute prediction and microstructure estimation are presentedLight transfer simulations based on optical properties are comprehensively discussedLeading groups are summarized for the first time, to the best of our knowledgeChallenges and prospects for optical property measurement are given [ABSTRACT FROM AUTHOR]

The study of complex geometric optics solutions to a system of d-bar equations appearing in the context of electrical impedance tomography and the scattering theory of the integrable Davey-Stewartson II equations for large values of the spectral parameter k in [C. Klein, J. Sjöstrand, and N. Stoilov, Comm. Pure Appl. Math., to appear] is extended to the reflection coefficient. For the case of potentials q with compact support on some domain Ω with smooth strictly convex boundary, improved asymptotic relations are provided. [ABSTRACT FROM AUTHOR]

We consider the repulsive Vlasov--Poisson system in dimension d ≥ 4. A condition on the decay rate of the associated electric field is presented that guarantees the scattering and determination of the complete asymptotic behavior of large data solutions as t∞. More specifically, we show that under this condition the spatial average of the particle distribution function converges, and we establish the precise asymptotic profiles of the electric field and macroscopic densities. An L∞ scattering result for the particle distribution function along the associated trajectories of free transport is also proved. Finally, we construct small data solutions that display this asymptotic behavior. These solutions do not require smallness of || f0|| ∞ or derivatives, as only a condition on integrated moments of the distribution function is imposed. [ABSTRACT FROM AUTHOR]

In this work, we consider the three-dimensional defocusing energy-critical nonlinear Schrödinger equation i\partial tu + Δ u = | u| 4u, (t,x) Є R × R³. Applying the incoming and outgoing decomposition presented in the recent work [M. Beceanu, Q. Deng, A. Soffer, and Y. Wu, Comm. Math. Phys., 382 (2021), pp. 173-237], we prove that for any radial function f with x ≤ 1f Є H¹ and x ≤ 1f Є Hs0 with 5/6 < s0 < 1, there exists an outgoing component f+ (or incoming component f) of f, such that when the initial data is f+, then the corresponding solution is globally well-posed and scatters forward in time; when the initial data is f-, then the corresponding solution is globally well-posed and scatters backward in time. [ABSTRACT FROM AUTHOR]

In this paper, we study the Cauchy problem for a generalized Boussinesq-type equation in R n . We establish a dispersive estimate for the linear group associated with the generalized Boussinesq-type equation. As applications, the global existence, decay and scattering of solutions are established for small initial data. [ABSTRACT FROM AUTHOR]

Generalized Lorenz–Mie theory (GLMT) is extensively utilized in the modelling and characterization of optical wave interaction with environmental aerosols. More specifically, the scattering of a Laguerre–Gaussian (LG) beam from a spherical marine aerosol particle is analyzed using the GLMT. By employing the GLMT and complex source point method, the scattering field coefficients of LG beams illuminating a marine aerosol particle are determined by implementing the boundary conditions on the surface of the marine aerosol. As compared to plane waves or Gaussian beams (GBs), the optical fields of LG beams are more tangled so their interaction with the target (i.e., marine aerosol particle) is also different. To detect change in the relative humidity (H r) of the marine aerosol, the LG beams are more effective. Influences of various parameters (i.e., radial mode p , azimuthal mode l , beam waist radius w 0 , beam wavelength (λ) , beam center locations (x 0 , y 0 , z 0) , and relative humidity (H r) ) on the differential scattering cross-section (DSCS) in far-field scattering are investigated. Thus, the DSCS caused by the marine aerosol particle can be tuned by selecting suitable parameters among those mentioned above. This research work can also help to elucidate the interaction between LG beams and spherical marine aerosol particles with layer structures. [ABSTRACT FROM AUTHOR]

Galperin introduced an interesting method to learn the digits of π by counting the collisions of two billiard balls and a hard wall. This paper studies two quantum versions of the Galperin billiards. It is shown that the digits of π can be observed in the phase shifts of the quantum models. [ABSTRACT FROM AUTHOR]

In d dimensions, accurately approximating an arbitrary function oscillating with frequency ≤ k requires ~kd degrees of freedom. A numerical method for solving the Helmholtz equation (with wavenumber k and in d dimensions) suffers from the pollution effect if, as k→ ∞, the total number of degrees of freedom needed to maintain accuracy grows faster than this natural threshold (i.e., faster than kd for domain-based formulations, such as finite element methods, and kd-1 for boundary-based formulations, such as boundary element methods). It is well known that the h-version of the finite element method (FEM) (where accuracy is increased by decreasing the meshwidth h and keeping the polynomial degree p fixed) suffers from the pollution effect, and research over the last ~30 years has resulted in a near-complete rigorous understanding of how quickly the number of degrees of freedom must grow with k to maintain accuracy (and how this depends on both p and properties of the scatterer). In contrast to the h-FEM, at least empirically, the h-version of the boundary element method (BEM) does not suffer from the pollution effect (recall that in the boundary element method the scattering problem is reformulated as an integral equation on the boundary of the scatterer, with this integral equation then solved numerically using a finite element-type approximation space). However, the current best results in the literature on how quickly the number of degrees of freedom for the h-BEM must grow with k to maintain accuracy fall short of proving this. In this paper, we prove that the h-version of the Galerkin method applied to the standard second-kind boundary integral equations for solving the Helmholtz exterior Dirichlet problem does not suffer from the pollution effect when the obstacle is nontrapping (i.e., does not trap geometric-optic rays). While the proof of this result relies on information about the large-k behavior of Helmholtz solution operators, we show in an appendix how the result can be proved using only Fourier series and asymptotics of Hankel and Bessel functions when the obstacle is a 2-d ball. [ABSTRACT FROM AUTHOR]

FRB 180916.J0158+65 is a well-known repeating fast radio burst with a period (⁠|$16.35~\rm d$|⁠) and an active window (⁠|$5.0~\rm d$|⁠). We give out the statistical results of the dispersion measures and waiting times of bursts of FRB 180916.J0158+65. We find the dispersion measures at the different frequencies show a bimodal distribution. The peaking dispersion measures of the left mode of the bimodal distributions increase with frequency, but the right one is inverse. The waiting times also present the bimodal distribution, peaking at 0.05622 and 1612.91266 s. The peaking time is irrelevant to the properties of bursts, either for the preceding or subsequent burst. By comparing the statistical results with possible theoretical models, we suggest that FRB 180916.J0158+65 suffered from the plasma lensing effects in the propagation path. Moreover, this source may be originated from a highly magnetized neutron star in a high-mass X-ray binary. [ABSTRACT FROM AUTHOR]

Surfactants in water and both alcohol‐water mixed solutions are used extensively in a host of industrial applications. This work presents the solution behavior and micellar transition of a cationic gemini surfactant (GS): N,N′‐dihexadecyl‐N,N,N′,N′‐tetramethyl‐N,N′‐ethanediyl‐diammonium dibromide (16‐2‐16) in water and mixed water‐ethanol media. Phase behavior for 16‐2‐16 in the ethanol–water system was investigated at ambient temperature. The rheological data obtained for these systems at varying alcohol concentrations showed that the system viscosity (η) decreased with as the ethanol concentration increased. Small‐angle neutron scattering (SANS) was used to probe the structural details of the cationic micelles as a function of ethanol concentration and temperature. The scattering data inferred a structural transition from unilamellar vesicles (ULV) through rod‐like micelles to ellipsoidal micelles occurs that is dependent on the solvent composition and temperature indicating the behavior of ethanol molecules as a cosolvent in the process of micelle breaking. The plausible physicochemical interactions in the 16‐2‐16‐ethanol mixed system were further investigated using a computational simulation study employing density functional theory (DFT)/B3LYP (Gauss View 5.0.9) utilizing a 3‐21G basis set. [ABSTRACT FROM AUTHOR]

Context. Recent spacecraft observations in the inner heliosphere have revealed the presence of local Alfvénic reversals of the magnetic field, while the field magnitude remains almost constant. These are called magnetic switchbacks (SBs) and are very common in the plasma environment close to the Sun explored by the Parker Solar Probe satellite. Aims. A simple numerical model of a magnetic field reversal with constant magnitude is used in order to explore the influence of SBs on the propagation of energetic particles within a range of energy typical of solar energetic particles. Methods. We model the reversal as a region of space of adjustable size bounded by two rotational discontinuities. By means of test particle simulations, beams of mono-energetic particles can be injected upstream of the SB with various initial pitch- and gyro-phase angles. In each simulation, the particle energy may also be changed. Results. Particle dynamics is highly affected by the ratio between the particle gyroradius and the size of the SB, with multiple pitch-angle scatterings occurring when the particle gyroradius is of the order of the SB size. Further, particle motion is extremely sensitive to the initial conditions, implying a transition to chaos; for some parameters of the system, a large share of particles is reflected backwards upstream as they interact with the SB. These results could have a profound impact on our understanding of solar energetic particle transport in the inner heliosphere, and therefore possible comparisons with in situ spacecraft data are discussed. [ABSTRACT FROM AUTHOR]

Context. The abundance and distribution of ice in protoplanetary disks is critical for an understanding of the link between the composition of circumstellar matter and the composition of exoplanets. Edge-on protoplanetary disks are a useful tool for constraining this ice composition and its location in the disk because the spectral signatures of the ice can be observed in absorption against the continuum emission that arises from the warmer regions in the central disk. Aims. The aim of this work is to model ice absorption features in protoplanetary disks and to determine how well the abundance of the main ice species throughout the disk can be determined within the uncertainty of the physical parameter space. The edge-on proto-planetary disk around HH 48 NE, a target of the James Webb Space Telescope Early Release program Ice Age, is used as a reference system. Methods. We used the full anisotropic scattering capabilities of the radiative transfer code RADMC-3D to ray-trace the mid-infrared continuum. Using a constant parameterized ice abundance, we added ice opacities to the dust opacity in regions in which the disk was cold enough for the main carbon, oxygen, and nitrogen carriers to freeze out. Results. The global abundance relative to the dust content of the main ice carriers in HH 48 NE can be determined within a factor of 3 when the uncertainty of the physical parameters is taken into account. Ice features in protoplanetary disks can be saturated at an optical depth of ≲1 due to local saturation. Ices are observed at various heights in the disk model, but in this model, spatial information is lost for features at wavelengths >7 µm when observing with James Webb Space Telescope because the angular resolution decreases towards longer wavelengths. Spatially observed ice optical depths cannot be directly related to column densities, as would be the case for direct absorption against a bright continuum source, because of radiative transfer effects. Vertical snowlines will not be a clear transition because the height of the snow surface increases radially, but their location may be constrained from observations using radiative transfer modeling. Radial snowlines are not really accessible. Not only the ice abundance, but also the inclination, the settling, the grain size distribution, and the disk mass have a strong impact on the observed ice absorption features in disks. Relative changes in the ice abundance can only be inferred from observations if the source structure is well constrained. [ABSTRACT FROM AUTHOR]

Context. Observations of edge-on disks are an important tool for constraining general protoplanetary disk properties that cannot be determined in any other way. However, most radiative transfer models cannot simultaneously reproduce the spectral energy distributions (SEDs) and resolved scattered light and submillimeter observations of these systems because the geometry and dust properties are different at different wavelengths. Aims. We simultaneously constrain the geometry of the edge-on protoplanetary disk HH 48 NE and the characteristics of the host star. HH 48 NE is part of the JWST early-release science program Ice Age. This work serves as a stepping stone toward a better understanding of the physical structure of the disk and of the icy chemistry in this particular source. This type of modeling lays the groundwork for studying other edge-on sources that are to be observed with the JWST. Methods. We fit a parameterized dust model to HH 48 NE by coupling the radiative transfer code RADMC-3D and a Markov chain Monte Carlo framework. The dust structure was fit independently to a compiled SED, a scattered light image at 0.8 µm, and an ALMA dust continuum observation at 890 µm. Results. We find that 90% of the dust mass in HH 48 NE is settled to the disk midplane. This is less than in average disks. The atmospheric layers of the disk also exclusively contain large grains (0.3–10 µm). The exclusion of small grains in the upper atmosphere likely has important consequences for the chemistry because high-energy photons can penetrate very deeply. The addition of a relatively large cavity (~50 au in radius) is necessary to explain the strong mid-infrared emission and to fit the scattered light and continuum observations simultaneously. [ABSTRACT FROM AUTHOR]

Radiation pressure on dust is an important feedback process around star clusters and may eject gas from bright subregions in star-forming galaxies. The Eddington ratio has previously been constructed for galaxy-averaged observations, individual star clusters, and Galactic H  ii regions. Here we assess the role of radiation pressure in thousands of subregions across two local star-forming galaxies, NGC 6946 and NGC 5194. Using a model for the spectral energy distribution from stellar population synthesis and realistic dust grain scattering and absorption, we compute flux and radiation pressure-mean opacities and population-averaged optical depth 〈τRP〉. Using Monte-Carlo calculations, we assess the momentum coupling through a dusty column to the stellar continuum. Optically-thin regions around young stellar populations are 30–50 times super-Eddington. We calculate the Eddington ratio for the subregions including the local mass of young and old stars and cool atomic and molecular gas. We compute the fraction of the total star formation that is currently super-Eddington, and provide an assessment of the role of radiation pressure in the dusty gas dynamics. Depending on the assumed height of the dusty gas and the age of the stellar population, we find that ∼0–10 per cent of the sightlines are super-Eddington. These regions may be accelerated to ∼5–15 km s−1 by radiation pressure alone. Additionally, our results show that for beamed radiation, the function 1 − exp (−〈τRP〉) is an excellent approximation to the momentum transfer. Opacities and optical depths are tabulated for SEDs of different stellar ages and for continuous star formation. [ABSTRACT FROM AUTHOR]

The properties of optical coatings play an important role in precision experiments. Gravitational-wave detectors not only require the highest quality coatings but also ones with relatively large diameters. Coatings made with amorphous material can be scaled up easily but for now exhibit relatively high thermal noise characteristics. Crystalline coatings show great promise in terms of their thermal noise properties but cannot easily scale up to the needed sizes. In this paper we explore the possibility of a piecewise coating that includes both amorphous and crystalline material. Specifically, we estimate the scattering losses of such a piecewise coating as a function of the mismatch in the interface between the two coatings. The calculation should be taken as a lower limit to the total losses, as other surface imperfections will play an important role in the final result, but are not considered here. Finally, we present a measurement of the scattering losses from a piecewise coating, to showcase the challenges of realizing such a design. [ABSTRACT FROM AUTHOR]

Two approaches based on gamma scattering technique (GST) and gamma transmission technique (GTT) have been devised and evaluated for measuring the density of polymers. The approach consists of combining Monte Carlo simulation and experimental data to determine the polymer density. The reliability of the proposed approaches is verified by experimental measurements with nine different polymers. The average relative deviation between the measured and the reference densities is under 2% for both two approaches. For the uncertainty of measured density, the GST yields better results with an average relative uncertainty of 1.61%, while this value for the GTT is 5.67%. [ABSTRACT FROM AUTHOR]

Atmospheric turbidity is one of the key factors influencing the propagation of artificial light into the environment during cloudless nights. High aerosol loading can reduce the visibility of astronomical objects, and thus information on atmospheric pollution is critical for the prediction of the night sky brightness (NSB) distribution. In particular, the aerosol optical depth (AOD) and asymmetry parameter (g) are among the most important aerosol properties influencing the NSB amplitudes. However, these two parameters are rarely available at astronomical sites. Here, we develop a method for AOD and g retrievals from clear-sky radiometry carried out around sunset or sunrise, shortly before or after night-time observation is intended. The method allows for reducing the number of unknowns needed in the processing and interpretation of night sky radiances, and thus provides an efficient tool for gathering input data to present skyglow simulators. The practice of collecting information about aerosols in this way could become a routine part of astronomical observations, much like observing standard stars to obtain extinction coefficients. If the procedure were conducted around sunset and the data were quickly reduced, it could offer an on-the-spot estimate of the NSB for the night ahead. The error analysis is performed using the theoretical model, while taking into account experimental errors of radiance readings. The capability of the method is demonstrated in a field experiment conducted under cloudless conditions. [ABSTRACT FROM AUTHOR]

Among all closed-shell species observed in molecular clouds, molecules with C3 v symmetry play a crucial role, as their rotational spectroscopy allows them to behave as a gas thermometer. In the interstellar medium, methyl cyanide (CH3CN) is the second most abundant of those (after ammonia, NH3). Its isomer, methyl isocyanide (CH3NC), is less abundant but has been detected in many astrophysical sources. In order to assess their absolute and relative abundances, it is essential to understand their collisional excitation properties. This paper reports the calculation of rate coefficients for rotational excitation of CH3CN and CH3NC molecules with He atoms, from low (5 K) to moderate (100 K) temperatures. We include the first 74 and 66 rotational states of both para and ortho symmetries of CH3CN and CH3NC, respectively. A propensity for Δ j = 2 transitions is observed in the case of CH3CN-He collisions, whereas in the case of CH3NC-He a propensity for Δ j = 1 is observed for transitions involving low values of j and at low temperatures, a propensity for Δ j = 2 is observed for higher values of j and at high temperatures. A comparison of rate coefficients shows differences up to a factor of 3, depending on temperature and on the ortho / para symmetries for dominant transitions. This confirms the importance of having specific collisional data for each isomer. We also examined the effect of these new rates on the CH3CN and CH3NC excitation in molecular clouds by performing radiative transfer calculations of the excitation and brightness temperatures for several detected lines. [ABSTRACT FROM AUTHOR]

The sharp range of Sobolev spaces is determined in which the Cauchy problem for the classical Zakharov system is well-posed, which includes existence of solutions, uniqueness, persistence of initial regularity, and real-analytic dependence on the initial data. In addition, under a condition on the data for the Schrödinger equation at the lowest admissible regularity, global well-posedness and scattering are proved. The results cover energy-critical and energy-supercritical dimensions d ≥ 4. [ABSTRACT FROM AUTHOR]

Analytic solutions are derived for the problem of scattering of obliquely incident plane waves from a rectangular crack in a fluid-saturated porous solid. The propagation direction and polarization direction of the incident waves can be arbitrary. The solutions are based on expanding the crack opening displacements in terms of Chebyshev functions. Explicit expressions for the frequency-dependent stress intensity factors and scattering far fields are obtained. The poroelastic effects play a key role in determining the crack opening mode by changing the effective normal stress applied on the crack surfaces. Consequently, the dynamic responses of the crack can be quite different from those of conventional dry crack in an elastic solid. The effects of scattered slow-P waves as well as wave-induced crack fluid pressure on the dynamic stress intensity factors are clarified, and a corner effect is observed in the scattering patterns for moderately high frequencies. The comparisons of synthetic seismograms with the elastic model show the slow-P waves can cause significant energy loss and waveform change. This study can be used for fracture analysis of porous media and nondestructive testing for individual hydraulic fractures in reservoirs. [ABSTRACT FROM AUTHOR]

The present study examines the co-micellization in different block copolymers (BCPs): P123 and F127 (with almost similar hydrophobic PO block but different hydrophilic %EO content). In varying concentration and in presence of NaCl, these BCP solutions in single and mix system displayed a variety of phases, i.e., blue point (BP), thermoreversible gel formation and cloud point (CP) with a noticeable sol–gel phase transition shift. The nanoscale micellar size distribution expressed as hydrodynamic diameter (Dh) was evaluated using dynamic light scattering (DLS). As F127 is larger than P123 and contains more EO groups, the micelle corona appears larger with greater Dh. The scattering profile from small-angle x-ray scattering (SAXS) offered information into the micellar dimensions employing SasView 4.2.2 program. The quercetin (QCT) solubilization articulated in encapsulation efficiency (EE%) and drug loading (DL%) followed the enhancement order: P123 > (P123 + F127) > F127 which was inferred from spectral and microscopy study. 5%w/v Pluronics® (P123 and F127) in single (pure) and mix environment depicting their micellar dimensions obtained from SAXS. [ABSTRACT FROM AUTHOR]

We establish global-in-time averaging for the L2-critical dispersion-managed nonlinear Schrödinger equation in the fast dispersion management regime. In particular, in the case of nonzero average dispersion, we establish averaging with any subcritical data, while in the case of a strictly positive dispersion map, we obtain averaging for data in L2. [ABSTRACT FROM AUTHOR]

The use of equipment such as oscilloscopes, high-speed cameras or acoustic sensors is quite common to measure detonation times from surface connectors and detonators. However, these solutions are expensive and, sometimes, not adequate to use in field conditions, such as mining or civil works. In this regard, a low-cost portable device is designed and tested using the Arduino platform, achieving a simple, robust and precise system to carry out field measurements. This study describes the characteristics and working principles of the designed device, as well as the verifications carried out to check the accuracy of the Arduino ceramic oscillator. Additionally, a field test was carried out using 100 actual detonators and surface connectors to verify the correct operation of the designed equipment. We have designed a device, and a methodology, to measure detonation instants with a minimum accuracy of 0.1 ms, being sufficient to carry out subsequent studies of detonation time dispersion for non-electric detonators. [ABSTRACT FROM AUTHOR]

We consider in a two dimensional absorbing and scattering medium, an inverse source problem in the stationary radiative transport, where the source is linearly anisotropic. The medium has an anisotropic scattering property that is neither negligible nor large enough for the diffusion approximation to hold. The attenuating and scattering properties of the medium are assumed known. For scattering kernels of finite Fourier content in the angular variable, we show how to recover the anisotropic radiative sources from boundary measurements. The approach is based on the Cauchy problem for a Beltrami-like equation associated with A-analytic maps. As an application, we determine necessary and sufficient conditions for the data coming from two different sources to be mistaken for each other. [ABSTRACT FROM AUTHOR]

This work studies the three space dimensional focusing inhomogeneous Schrödinger equation with inverse square potential i ∂ t u − (− Δ + λ | x | 2 ) u + | x | − 2 τ | u | 2 (q − 1) u = 0 , u (t , x) : R × R 3 → C. The purpose is to investigate the energy scattering of global inter-critical solutions below the ground state threshold. The scattering is obtained by using the new approach of Dodson-Murphy, based on Tao's scattering criteria and Morawetz estimates. This work naturally extends the recent paper by J. An et al. (Discrete Contin. Dyn. Syst., Ser. B 28(2): 1046–1067 2023). The threshold is expressed in terms the non-conserved potential energy. As a consequence, it can be given with a classical way with the conserved mass and energy. The inhomogeneous term | x | − 2 τ for τ > 0 guarantees the existence of ground states for λ ≥ 0 , contrarily to the homogeneous case τ = 0 . Moreover, the decay of the inhomogeneous term enables to avoid any radial assumption on the datum. Since there is no dispersive estimate of L 1 → L ∞ for the free Schrödinger equation with inverse square potential for λ < 0 , one restricts this work to the case λ ≥ 0 . [ABSTRACT FROM AUTHOR]

We have studied the asymmetric transmission in diffractive chiral metasurfaces consisting of nanoantennas. The study was made of lattice plasmon modes on the phenomenon of asymmetric transmission in chiral two dimensional arrays of plasmonic nanoparticles. It was demonstrated that asymmetric transmission resulted from contribution of higher order diffracted waves. It was shown that the isolated nanostructures has a fourfold rotational symmetry, the diffractive metasurfaces exhibited asymmetric transmission for normal incidence light within spectral range for which lattice plasmon modes were supported. It was found that lattice plasmon modes played role in enabling symmetric transmission in diffractive chiral metasurfaces. The symmetric transmission mechanism is due to different lattice plasmon mode excitation efficiencies of left circularly polarized and right circularly polarized and right circularly polarized light. The excitation efficiencies are controlled by tailoring the nano particles in plan distribution of scattered light for circularly polarized excitation and its alignment with the inplane diffraction orders of the metasurfaces. The phenomenon for a metasurface composed of an array of a chiral nanoparticles consisting of four nanoantennas. It was shown that the Rayleigh anomaly condition where the asymmetric transmission effect was strongest and metasurfaces supported lattice plasmon modes. It was found that the difference in the inplane scattered intensity varied as a function of the inplane angle around the nanostructure, rotating the nanostructure in the plane of the metasurface. The obtained results found in good agreement with previously obtained results. [ABSTRACT FROM AUTHOR]

Introduction: Quantitative accuracy in SPECT is mainly affected by collimator penetration and scattering, particularly for high-energy imaging. Lofthole collimation offers superior performance in terms of penetration and scattering. Methods: In this research, the GATE Monte Carlo simulator was exploited to calculate edge penetration and scattering in the lofthole collimator using an inair and in-phantom point source of Tc-99m and I-123. The performance of the lofthole was then compared to that of a pinhole. Both lofthole and pinhole collimators were assumed to have the same geometry including an aperture diameter of 3.04 mm and an opening angle of 75°. Furthermore, the angular distribution of the scattering and penetration were investigated for a multilofthole collimator. Results: The results show that penetration, scattering, and sensitivity are all a function of the photon energy. The penetration and scattering of the pinhole are about 4% higher than that of the lofthole collimator, for Tc-99m SPECT. Compared to the Tc-99m, I-123 SPECT suffers from approximately 1.5- and 1.42-fold higher penetration and scatter fractions, respectively, for lofthole aperture. Moreover, the lofthole collimator presents a higher sensitivity compared with the pinhole (0.030 versus 0.023 for the Tc-99m SPECT). In addition, the findings exhibit a reduction in sensitivity by increasing the photon incidence angle. Both scattering and penetration fractions illustrate a decreasing trend across the angle of incidence. Conclusion: Compared to pinhole, the lofthole offers superior performance in terms of scattering and penetration for both low- and high-energy SPECT imaging. [ABSTRACT FROM AUTHOR]

In our paper, a stirrer made of a polarization converter for a reverberation chamber (RC) is proposed. A cylindrical polarization converter (PC) stirrer with two unit structures arranged alternatively is placed in RC to take the place of a traditional metallic stirrer. Because of the scattering property of the PC stirrer, it is possible to enlarge the working volume and improve the scattering performance of the stirrer in the RC while maintaining the field uniformity and field anisotropy coefficient to meet the testing standard of the International Electrotechnical Commission 61000‐4‐21. Metallic stirrer and PC stirrer are both placed in the RC simultaneously to make a measurement for guaranteeing the same testing environment. Some parameters of the RC stirred by the PC stirrer or metallic stirrer have been measured and analyzed, such as field uniformity, field anisotropy, coefficient independent sample number and total scattering cross‐section (TSCS), and so on. Testing results verify that the RC stirred by a PC stirrer outperforms the classic RC stirred by a conventional metallic stirrer in terms of some performance, indicating that the proposal has a significant impact on RC testing technology that requires a larger working volume and better TSCS. [ABSTRACT FROM AUTHOR]

We consider the focusing inhomogeneous nonlinear Schrödinger equation in H¹(R³), i∂tu + Δu + |x|-b|u|²u = 0, where 0 < b < 1/2. Previous works (see, e.g., [L. Campos, Nonlinear Anal., 202 (2021), 112118; L. G. Farah and C. M. Guzmán, J. Differential Equations, 262 (2017), pp. 4175--4231; J. Murphy, Proc. Amer. Math. Soc., 150 (2022), pp. 1177--1186]) have established a blowup/scattering dichotomy below a mass-energy threshold determined by the ground state solution Q. In this work, we study solutions exactly at this mass-energy threshold. In addition to the ground state solution, we prove the existence of solutions Q±, which approach the standing wave in the positive time direction but either blow up or scatter in the negative time direction. Using these particular solutions, we classify all possible behaviors for threshold solutions. In particular, the solution either behaves as in the subthreshold case, or it agrees with eitQ, Q+, or Q- up to the symmetries of the equation. [ABSTRACT FROM AUTHOR]

We consider Cauchy problem of Hartree-type nonlinear Dirac equation with potentials given by Vb(x) = ... (b ≤ 0). In previous works regarding a global well-posedness of Dirac equation with these potentials, a standard argument is to utilize null form estimates in order to prove global well-posedness for Hs-data, s > 0. However, the null structure inside the equations is not enough to attain critical regularity. We impose an extra regularity assumption with respect to the angular variable. First, we prove the global well-posedness and scattering of Dirac equations with Hartree-type nonlinearity for b > 0 for small L²x-data with additional angular regularity. We also show that only a small amount of angular regularity is required to obtain the global existence of solutions. Second, we obtain nonscattering result for a certain class of solutions with the Coulomb potential V0(x). [ABSTRACT FROM AUTHOR]

We consider a wide variety of Helmholtz scattering problems including scattering by Dirichlet, Neumann, and penetrable obstacles. We consider a radial perfectly matched layer (PML) and show that for any fixed PML width and a steep-enough scaling angle, the PML solution is exponentially close, both in frequency and the tangent of the scaling angle, to the true scattering solution. Moreover, for a fixed scaling angle and large enough PML width, the PML solution is exponentially close to the true scattering solution in both frequency and the PML width. In fact, the exponential bound holds with rate of decay c(wtan θ C)k, where w is the PML width and θ is the scaling angle. More generally, the results of the paper hold in the framework of black-box scattering under the assumption of an exponential bound on the norm of the cutoff resolvent, thus including problems with strong trapping. These are the first results on the exponential accuracy of PML at high-frequency with nontrivial scatterers. [ABSTRACT FROM AUTHOR]

In this manuscript, the electromagnetic (EM) radiation force (RF) exerted on a perfect electromagnetic conductor (PEMC) sphere by a vortex electromagnetic (VEM) wave with spiral phase distribution had been investigated. The analytical formulation of EM fields is being done in the framework of Mie theory, while the field expressions are being modeled considering the features of VEM wave for PEMC sphere. Initially, the incident field coefficients are evaluated using definite integrals. The scattering coefficients are then determined by imposing boundary conditions at the surface of PEMC sphere i.e., at r = a, leading to a linear system of equations computed via solving matrix. So, a lengthy calculation yields undetermined scattered field coefficients relative to incident field coefficients. The cross-section (Q) factors i.e., scattering (Qsca) and extinction (Qext) have been computed. The influence of sphere size parameter (p) and beam waist radius (wo) versus scattering angle (a) for the RF along with Qsca has been numerically analyzed. As no loss of energy occurs inside PEMC sphere so absorption ((Qabs) = 0), by virtue of the energy conservation principle then, Qext = Qsca. Under specific condition, we implemented present results on Qsca towards light without orbital angular momentum (OAM) i.e., (10) and plane wave for the PEMC sphere. The research work has potential applications = towards particle manipulation, optical technology, and optical tweezers. [ABSTRACT FROM AUTHOR]

We investigate the error in developing a technique for measuring the background concentration of methane by the passive location method using solar radiation as a source. Background concentration of methane is measured along three separate trajectories in a region northeast of Moscow. The first route passes through an urbanized area with developed infrastructure, industry and high population density; the second and third routes pass through areas with a lower population density and buildings, and have many forests and reservoirs. When processing measurement results, it was found that, along with random errors, it is necessary to take into account the systematic error due to the influence of external factors on measuring the methane background concentration during sounding under small angles to the horizon, when the path length noticeably increases. It is shown that such influencing factors can include the scattering of light by aerosols and other impurity particles in the atmosphere. Compensation adjustments have been made which reduced the systematic error to almost zero. A monitoring technique has been proposed that makes it possible to obtain a relative error in units of percent when measuring the background concentration of methane over a long duration. The results of the performed measurements are consistent with the results of global measurements and confirm the growth in the background concentration of methane in the Earth's atmosphere in recent years. [ABSTRACT FROM AUTHOR]

Collisional excitation of C5H+ by He was performed by mean of state-of-the-art methods. A high level of theory quantum chemical calculations were made to determine the interaction potential energy surface of C5H+ with helium. The new two-dimensional potential energy surface obtained from the RCCSD(T)-F12 ab initio approach associated with aug-cc-pVTZ basis sets, presents two minima below its dissociation limit with well depths of |$-101.8$| and |$-100.2\, \mathrm{cm}^{-1}$|. In order to derive accurate physical conditions from rotational transitions of the recently discovered C5H+ molecule in Taurus molecular cloud (TMC-1), rate coefficients calculations are performed. The C5H+(X1Σ+)–He de-excitation rates are obtained after averaging cross-sections for thermal temperature below 100 K. The integral cross-sections are computed with the close-coupling quantum time-independent formalism for |$E\le 520 \, \mathrm{cm}^{-1}$| and J ≤ 15. The new collisional data will allow accurate determination of the C5H+ abundance and will help to understand the chemistry of carbon chain ions in the interstellar gas. [ABSTRACT FROM AUTHOR]

We follow up on work of Strauss, Weder, and Watanabe concerning scattering and inverse scattering for nonlinear Schrödinger equations with nonlinearities of the form α (x) | u | p u . [ABSTRACT FROM AUTHOR]

Low-temperature variable-energy electron irradiation was used to induce non-magnetic disorder in a single crystal of a hole-doped iron-based superconductor, Ba 1 − x K x Fe 2 As 2 , x = 0.80. To avoid systematic errors, the beam energy was adjusted non-consequently for five values between 1.0 and 2.5 MeV when sample resistance was measured in situ at 22 K. For all energies, the resistivity raises linearly with the irradiation fluence suggesting the creation of uncorrelated dilute point-like disorder (confirmed by simulations). The rate of the resistivity increase peaks at energies below 1.5 MeV. Comparison with calculated partial cross-sections points to the predominant creation of defects in the iron sublattice. Simultaneously, superconducting T c , measured separately between the irradiation runs, is monotonically suppressed as expected, since it depends on the total scattering rate, hence on the total cross-section, which is a monotonically increasing function of the energy. Our work experimentally confirms an often-made assumption of the dominant role of the iron sub-lattice in iron-based superconductors. [ABSTRACT FROM AUTHOR]

This article describes the distribution of complex products of the amplitudes of randomly scattered signals observed at two points. The signals at the two points are assumed to be fully saturated (zero-mean real and imaginary parts) and partially correlated, and to have a variance that is randomly modulated by the environment (e.g. turbulence, vegetation, or terrain variations). These assumptions are shown to lead to a new distribution for the real and imaginary parts of the complex product, called the compound variance gamma ( CV Γ ), which involves a Gauss hypergeometric function. The CV Γ distribution generalizes the compound gamma ( C Γ ), which applies to one-point statistics with randomly modulated scattering, and the variance gamma ( V Γ ), which applies to two-point statistics without random modulation. The CV Γ is shown to provide an excellent fit to two-point statistics derived from realistic simulations of sound propagation in the atmosphere including turbulent scattering, refraction by wind and temperature gradients, and ground reflections. [ABSTRACT FROM AUTHOR]

Context. Lunar swirls are bright albedo features only found on the Moon that are still not entirely understood. It is commonly accepted that reduced space weathering plays a role in explaining the origins of lunar swirls because the local magnetic fields that are typically associated with these albedo anomalies are effective in reducing the solar wind influx. However, additional processes are required to fully explain the spectral, photometric, and polarimetric properties of the swirls. Aims. In this study, we compare the photometric properties of the Chang'e-5 landing site to those of the Reiner Gamma swirl. Because the physical effects of a landing rocket jet on the lunar regolith are relatively well known, these observations can provide important insights into the physical properties of lunar swirls. Methods. We determined the single scattering albedo, opposition effect strength, and surface roughness of the Reiner Gamma swirl and the Chang'e-5 landing site with their respective statistical uncertainties based on the Hapke model and Bayesian inference sampling. Results. The Chang'e-5 landing site and the Reiner Gamma swirl exhibit similar photometric properties, in particular: an increased albedo and a reduced opposition effect strength. Additionally, the landing site is about 20% less rough compared to the surrounding area. Conclusions. These findings suggest that the swirl surface is less porous compared to the surrounding surface, similarly to a landing site where the top layer of the regolith has been blown away effectively so that the compactness was increased. We conclude that external mechanisms that are able to compress the uppermost regolith layer are involved in lunar swirl formation, such as interactions with the gaseous hull of a passing comet. [ABSTRACT FROM AUTHOR]

This paper presents a study on in-plane wave propagation in two-dimensional polycrystalline microstructure with different grain distributions. The numerical simulations are performed using commercial finite element (FE) package and the microstructure is generated using Voronoi tessellation. The different grain distributions are generated using a regularity parameter, α. In-plane wave results in simultaneous P and S waves unlike conventional bulk wave, where only P or S wave is observed. Such in-plane wave propagation resulting from localized excitation is more realistic and has important applications in microstructural flaw detection. Here, an analogy is drawn with seismic wave in heterogeneous geophysical media to understand the in-plane waves in the polycrystalline microstructure. First, the effect of grain distributions on the attenuation and phase velocity behavior of in-plane wave is studied in the low-frequency Rayleigh regime. The numerical simulations are performed for Inconel-600 for grain sizes of 100 and 250 μ m . Then, the numerical model is validated with experimental results using piezoelectric transducers on an Inconel-600 plate. The physical microstructure of Inconel-600 material is observed using a scanning electron microscope. The frequency dependency of attenuation for in-plane waves is close to unity similar to that of seismic wave. The attenuation and phase velocity vary with the change in regularity parameter, α. Additionally, it is observed that the scattering of P wave is higher than that of S wave during in-plane wave propagation, resulting in higher attenuation of P wave. Finally, an exponential expression is established between regularity parameter and attenuation, which will help in characterizing and predicting the grain distribution inversely. [ABSTRACT FROM AUTHOR]

The present paper discusses the scattering phenomenon of Love-type wave on the functionally graded piezoelectric material (FGPEM) stratum overlying a functionally graded piezomagnetic material (FGPMM) substrate containing abrupt thickening at the uppermost free surface. The expressions for dispersion relation and group velocity (GV) are obtained for four kinds of electric-magnetic boundary conditions. The expressions for mechanical displacement (MD) component, electric potential (EP), and magnetic potential (MP) functions for stratum and substrate are deduced by using the perturbation method and residue theorem. The effect of piezoelectric and piezomagnetic coupling parameters and abrupt thickening parameters on phase velocity (PV), GV, MD component, and EP & MP functions associated with the stratum are graphically represented. A comparative study is carried out to delineate the concealed characteristics of wave on the considered model due to three different shaped abrupt thickening for four kinds of electric-magnetic boundary conditions (i.e. electrically short and magnetically short (ESMS), electrically open and magnetically short (EOMS), electrically open and magnetically open (EOMO), and electrically short and magnetically open (ESMO)). [ABSTRACT FROM AUTHOR]

We develop a Monte Carlo radiative transfer code to study the effect of turbulence with a finite correlation length on scattering of Ly α photons propagating through neutral atomic hydrogen gas. We investigate how the effective mean free path, the emergent spectrum, and the average number of scatterings that Ly α photons experience change in the presence of turbulence. We find that the correlation length is an important and sensitive parameter that has an influence on physically relevant properties of Ly α radiative transfer. In particular, it can significantly, by orders of magnitude, reduce the number of scattering events that the average Ly α photon undergoes before it escapes the turbulent cloud. [ABSTRACT FROM AUTHOR]

Our previous study on dissociative recombination of ground state SH+ through 2Π states of SH is extended by taking into account the contribution of 4Π states recently explored by quantum chemistry methods. Multichannel quantum defect theory is employed for the computation of cross sections and rate coefficients for dissociative recombination, but also for vibrational excitation. Furthermore, we produce the atomic yields resulting from recombination, quantifying the generation of sulfur atoms in their ground (3P) and lowest excited (1D) states, respectively. [ABSTRACT FROM AUTHOR]

Line-field Confocal Optical Coherence Tomography (LC-OCT) is an imaging modality based on a combination of time-domain optical coherence tomography and reflectance confocal microscopy. LC-OCT provides three-dimensional images of semi-transparent samples with a spatial resolution of ∼1 μm. The technique is primarily applied to in vivo skin imaging. The image contrast in LC-OCT arises from the backscattering of incident light by the sample microstructures, which is determined by the optical scattering properties of the sample, characterized by the scattering coefficient μs and the scattering anisotropy factor g. In biological tissues, the scattering properties are determined by the organization, structure and refractive indexes of the sample. The measurement of these properties using LC-OCT would therefore allow a quantitative characterization of tissues in vivo. We present a method for extracting the two scattering properties μs and g of tissue-mimicking phantoms from 3D LC-OCT images. The method provides the mean values of μs and g over a lateral field of view of 1.2 mm × 0.5 mm (x × y). It can be applied to monolayered and bilayered samples, where it allows extraction of μs and g of each layer. Our approach is based on a calibration using a phantom with known optical scattering properties and on the application of a theoretical model to the intensity depth profiles acquired by LC-OCT. It was experimentally tested against integrating spheres and collimated transmission measurements for a set of monolayered and bilayered scattering phantoms. [ABSTRACT FROM AUTHOR]

[Display omitted] The internal organization of polyelectrolyte layers deposited on colloidal templates plays a very important role for the potential applications of these systems as capsules for drug delivery purposes. The mutual arrangement of oppositely charged polyelectrolyte layers upon their deposition on positively charged liposomes has been studied by combining up three different scattering techniques and Electronic Spin Resonance, which has provided information about the inter-layer interactions and their effect on the final structure of the capsules. The sequential deposition of oppositely charged polyelectrolytes on the external leaflet of positively charged liposomes allows modulating the organization of the obtained supramolecular structures, impacting the packing and rigidity of the obtained capsules due to the change of the ionic cross-linking of the multi-layered film as a result of the specific charge of the last deposited layer. The possibility to modulate the properties of the LbL capsules by tuning the characteristics of the last deposited layers offers a very interesting route for the design of materials for encapsulation purposes with their properties controlled almost at will by changing the number of deposited layers and their chemistry. [ABSTRACT FROM AUTHOR]

We provide in this paper new Stark broadening parameters for the four ions Ga IV, Ga V, Ge IV, and Ge V. The calculations have been performed using our quantum mechanical method. To the best of our knowledge, the only available Stark broadening results are those of the Ge IV ion, where the semiclassical perturbation and the modified semi-empirical methods have been used. For the three other ions, no data have been found. In 2020 and for the first time, about five hundred lines of trans-iron elements including gallium (Ga) and germanium (Ge) have been identified in the ultraviolet (UV) spectrum of a DAO-type white dwarf BD-22°3467. Other precedent observations showed the existence of Ga IV–V lines in two white dwarfs (G191-B2B and RE 0503-289), and those of Ge IV and Ge V in the UV spectrum of RE 0503-289. Theoretical evaluations and measurements of atomic and Stark broadening data are a pre-requisite for stellar-atmosphere modelling, which is a tool for the determination of the photospheric Ga and Ge abundance in white dwarfs. Since there is no Stark broadening data for the three ions Ga IV, Ga V, and Ge V, our calculations come to fill this gap, and the obtained results can be used for the abundance determination of elements, the calculation of stellar opacity, the interpretation and modelling of stellar spectra, and the estimation of the relative transfer through stellar plasmas. They will be also implemented into the data base of Stark broadening parameters, STARK-B. [ABSTRACT FROM AUTHOR]

We present a new analysis of the Suzaku X-ray spectrum of the Compton-thin Seyfert 2 galaxy NGC 4388. The spectrum above ∼2 keV can be described by a remarkably simple and rather mundane model, consisting of a uniform, neutral spherical distribution of matter, with a radial column density of |$2.58\pm 0.02 \times 10^{23} \ \rm cm^{-2}$|⁠ , and an Fe abundance of |$1.102^{+0.024}_{-0.021}$| relative to solar. The model does not require any phenomenological adjustments to self-consistently account for the low-energy extinction, the Fe Kα and Fe Kβ fluorescent emission lines, the Fe K edge, and the Compton-scattered continuum from the obscuring material. The spherical geometry is not a unique description, however, and the self-consistent, solar abundance MYTORUS model, applied with toroidal and non-toroidal geometries, gives equally good descriptions of the data. In all cases, the key features of the spectrum are so tightly locked together that for a wide range of parameters, a relativistic disc-reflection component contributes no more than |$\sim 2{{\ \rm per\ cent}}$| to the net spectrum in the 2–20 keV band. We show that the commonly invoked explanations for weak X-ray reflection features, namely a truncated and/or very highly ionized disc, do not work for NGC 4388. If relativistically broadened Fe Kα lines and reflection are ubiquitous in Seyfert 1 galaxies, they should also be ubiquitous in Compton-thin Seyfert 2 galaxies. The case of NGC 4388 shows the need for similar studies of more Compton-thin AGN to ascertain whether this is true. [ABSTRACT FROM AUTHOR]

Using a quantum-mechanical close-coupling method, we calculate cross-sections for fine-structure excitation and relaxation of Si and S atoms in collisions with atomic hydrogen. Rate coefficients are calculated over a range of temperatures for astrophysical applications. We determine the temperature-dependent critical densities for the relaxation of Si and S in collisions with H and compare these to the critical densities for collisions with electrons. The present calculations should be useful in modelling environments exhibiting the [S  i ] 25 μm and [S  i ] 57 μm far-infrared emission lines or where cooling of S and Si by collisions with H is of interest. [ABSTRACT FROM AUTHOR]

In this note, we show the existence of a special solution u to defocusing cubic NLS in 3d, which lives in H^{s} for all s>0, but scatters to a linear solution in a very slow way. We prove for this u, for all \epsilon >0, one has \sup _{t>0}t^{\epsilon }\|u(t)-e^{it\Delta }u^{+}\|_{\dot {H}^{1/2}}=\infty. Note that such a slow asymptotic convergence is impossible if one further pose the initial data of u(0) be in L^{1}. We expect that similar construction hold the for other NLS models. It can been seen the slow convergence is caused by the fact that there are delayed backward scattering profile in the initial data, we also illustrate why L^{1} condition of initial data will get rid of this phenomena. [ABSTRACT FROM AUTHOR]

The resonance of a plasma column with an elliptical cross-section surrounded by a dielectric layer is investigated. It is assumed that the incident electromagnetic wave has a wavelength much larger than the dimensions of the assumed cross-section of the column. Using boundary conditions, the electric potentials and resonant frequencies of an elliptical plasma column covered by a dielectric for two polarisations of incident electric field are calculated. The incident electric field is considered in directions of the minor and major axes of the boundary ellipse. The limit cases are examined. The dependence of the resonant frequency on the dielectric constant and the plasma and dielectric dimensions are investigated. The obtained results are drawn and analysed. Then an elliptical plasma column with a coaxial dielectric core and a dielectric layer in scattering process by long wavelength waves is considered and the resonant frequencies of this object for two polarisations of incident electric field are calculated. The obtained results are plotted and analysed. This configuration can be presented as a plasma antenna. [ABSTRACT FROM AUTHOR]

We present in this paper new quantum Half Widths at Half intensity Maximum (HWHM) for 101 spectral lines of the following ions: O II (35 lines), O III (20 lines), Si II (9 lines), Si III (12 lines), and Al III (25 lines). The present quantum results are compared to new experimental ones. No previous quantum calculations have been performed for these ions. The relatively high differences found between the new and previous measurements and the available theoretical calculations encourage us to conduct these quantum calculations. Our quantum method has been used many years ago and has given good results compared to other approaches, so it can be a useful tool to check the new experimental results or to understand the disagreement found for some lines. Furthermore, the obtained results can be used for the abundance determination of elements, the calculation of stellar opacity, the interpretation and modelling of stellar spectra, and the estimation of the relative transfer through stellar plasmas, etc. Part of the present results will be also implemented to the data base of Stark broadening parameters STARK-B. [ABSTRACT FROM AUTHOR]