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The molecular foundations of epidermal cell wall mechanics are critical for understanding structure-function relationships of primary cell walls in plants and facilitating the design of bioinspired materials. To uncover the molecular mechanisms regulating the high extensibility and strength of the cell wall, the onion epidermal wall is stretched uniaxially to various strains and cell wall structures from mesoscale to atomic scale are characterized. Upon longitudinal stretching to high strain, epidermal walls contract in the transverse direction, resulting in a reduced area. Atomic force microscopy shows that cellulose microfibrils exhibit orientation-dependent rearrangements at high strains: longitudinal microfibrils are straightened out and become highly ordered, while transverse microfibrils curve and kink. Small-angle X-ray scattering detects a 7.4 nm spacing aligned along the stretch direction at high strain, which is attributed to distances between individual cellulose microfibrils. Furthermore, wide-angle X-ray scattering reveals a widening of (004) lattice spacing and contraction of (200) lattice spacing in longitudinally aligned cellulose microfibrils at high strain, which implies longitudinal stretching of the cellulose crystal. These findings provide molecular insights into the ability of the wall to bear additional load after yielding: the aggregation of longitudinal microfibrils impedes sliding and enables further stretching of the cellulose to bear increased loads.

In this article we investigate novel signatures of radiation reaction via the angular deflection of an electron beam colliding at 90 degrees with an intense laser pulse. Due to the radiation reaction effect, the electrons can be deflected towards the beam axis for plane wave backgrounds, which is not possible in the absence of radiation reaction effects. The magnitude and size of the deflection angle can be controlled by tailoring the laser pulse shapes. The effect is first derived analytically using the Landau-Lifshitz equation, which allows to determine the important scaling behavior with laser intensity and particle energy. We then move on to full scale 3D Monte Carlo simulations to verify the effect is observable with present day laser technology. We investigate the opportunities for an indirect observation of laser depletion in such side scattering scenarios.

The axon-initial-segment (AIS) of mature neurons contains microtubule (MT) fascicles (linear bundles) implicated as retrograde diffusion barriers in the retention of MT-associated protein (MAP) tau inside axons. Tau dysfunction and leakage outside of the axon is associated with neurodegeneration. We report on the structure of steady-state MT bundles in varying concentrations of Mg2+ or Ca2+ divalent cations in mixtures containing αβ-tubulin, full-length tau, and GTP at 37 °C in a physiological buffer. A concentration-time kinetic phase diagram generated by synchrotron SAXS reveals a wide-spacing MT bundle phase (Bws), a transient intermediate MT bundle phase (Bint), and a tubulin ring phase. SAXS with TEM of plastic-embedded samples provides evidence of a viscoelastic intervening network (IN) of complexes of tubulin oligomers and tau stabilizing MT bundles. In this model, αβ-tubulin oligomers in the IN are crosslinked by taus MT binding repeats, which also link αβ-tubulin oligomers to αβ-tubulin within the MT lattice. The model challenges whether the cross-bridging of MTs is attributed entirely to MAPs. Tubulin-tau complexes in the IN or bound to isolated MTs are potential sites for enzymatic modification of tau, promoting nucleation and growth of tau fibrils in tauopathies.

Electron bifurcation (BF) is an evolutionarily ancient energy coupling mechanism in anaerobes, whose associated enzymatic machinery remains enigmatic. In BF-flavoenzymes, a chemically high-potential electron forms in a thermodynamically favorable fashion by simultaneously dropping the potential of a second electron before its donation to physiological acceptors. The cryo-EM and spectroscopic analyses of the BF-enzyme Fix/EtfABCX from Thermotoga maritima suggest that the BF-site contains a special flavin-adenine dinucleotide and, upon its reduction with NADH, a low-potential electron transfers to ferredoxin and a high-potential electron reduces menaquinone. The transfer of energy from high-energy intermediates must be carefully orchestrated conformationally to avoid equilibration. Herein, anaerobic size exclusion-coupled small-angle X-ray scattering (SEC-SAXS) shows that the Fix/EtfAB heterodimer subcomplex, which houses BF- and electron transfer (ET)-flavins, exists in a conformational equilibrium of compacted and extended states between flavin-binding domains, the abundance of which is impacted by reduction and NAD(H) binding. The conformations identify dynamics associated with the T. maritima enzyme and also recapitulate states identified in static structures of homologous BF-flavoenzymes. Reduction of Fix/EtfABCX's flavins alone is insufficient to elicit domain movements conducive to ET but requires a structural "trigger" induced by NAD(H) binding. Models show that Fix/EtfABCX's superdimer exists in a combination of states with respect to its BF-subcomplexes, suggesting a cooperative mechanism between supermonomers for optimizing catalysis. The correlation of conformational states with pathway steps suggests a structural means with which Fix/EtfABCX may progress through its catalytic cycle. Collectively, these observations provide a structural framework for tracing Fix/EtfABCX's catalysis.

Skyglow from sources of artificial light at night poses a significant challenge to ground-based astronomical research and discovery. Although astronomers, conservationists, and light-pollution researchers have measured skyglow for decades, their data on diffuse night-time light fields are incomplete as they lacks information about the polarization state of the light. Here, we present the first successful theoretical model that predicts the degree and angle of linear polarization of scattered night sky light and accounts for complex, real-world distributions of ground light sources. The model proceeds from an analytical solution to the polarized radiative transfer equation that is validated by field experiments. We discuss several use cases of the model and demonstrate its practical consequences, such as the ability to more reliably determine which ground sources in the area around an observer contribute the most scattered light in a given sky element. [ABSTRACT FROM AUTHOR]

The eclipses seen in the radio emission of some pulsars can be invaluable to study the properties of the material from the companion stripped away by the pulsar. We present a study of six consecutive eclipses of PSR J0024–7204O in the globular cluster 47 Tucanae as seen by the MeerKAT radio telescope in the UHF (544–1088 MHz) band. A high scintillation state boosted the signal during one of the orbits and allowed a detailed study of the eclipse properties. We measure significant dispersion measure (DM) variations and detect strong scattering that seems to be the dominating mechanism of the eclipses at these frequencies. A complete drop in the linear polarization together with a small increase in the rotation measure suggests the presence of a magnetic field of |$\sim 2$|  mG. The study of multiple eclipses allowed us to measure difference in the lengths of the eclipses and DM differences of |$\sim 0.01$|  pc cm |$^{-3}$| in consecutive orbits. One orbit, in particular, shows a delay in recovery of the linear polarization and a visible delay in the arrival of the pulses caused by a stronger scattering event. We suggest that these are caused by a higher variance of density fluctuations during the event. [ABSTRACT FROM AUTHOR]

The Mg ii resonance doublet at 2796 Å and 2803 Å is an increasingly important tool to study cold, |$T \sim 10^{4}\,$|  K, gas – an observational-driven development requiring theoretical support. We develop a new Monte Carlo radiative transfer code to systematically study the joined Mg ii and Ly α escape through homogeneous and 'clumpy' multiphase gas with dust in arbitrary three-dimensional geometries. Our main findings are (i) the Mg ii spectrum differs from Ly α due to the large difference in column densities, even though the atomic physics of the two lines are similar. (ii) The Mg ii escape fraction is generally higher than that of Ly α because of lower dust optical depths and path lengths – but large variations due to differences in dust models and the clumpiness of the cold medium exist. (iii) Clumpy media possess a 'critical covering factor' above which Mg ii radiative transfer matches a homogeneous medium. The critical covering factors for Mg ii and Ly α differ, allowing constraints on the cold gas structure. (iv) The Mg ii doublet ratio |$R_{\rm MgII}$| varies for strong outflows/inflows (⁠|$\gtrsim 700 \,\mathrm{km\, s}^{-1}$|⁠), in particular, |$R_{\rm MgII}\lt 1$| being an unambiguous tracer for powerful galactic winds. (v) Scattering of stellar continuum photons can decrease |$R_{\rm MgII}$| from two to one, allowing constraints on the scattering medium. Notably, we introduce a novel probe of the cold gas column density – the halo doublet ratio – which we show to be a powerful indicator of ionizing photon escape. We discuss our results in the context of interpreting and modelling observations as well as their implications for other resonant doublets. [ABSTRACT FROM AUTHOR]

This study uses an analytical method to examine the scattering of a Love wave from an interfacial crack in a thin lossy media (viscoelastic material) that serves as a waveguide layer attached to an unbounded loss-less media (piezoelectric material). The viscoelastic material is modeled using the Kelvin–Voigt equation. Phase velocity and attenuation have been calculated by equating the real and imaginary parts of the dispersion relation to zero, respectively, due to the complex wave number of viscoelastic material. Using the integral transform approach and the dislocation density function, the scattering field close to the crack tip is determined, resulting in a Cauchy singular integral equation of the first type. It has been transformed into a system of linear algebraic equations using Gauss-Chebyshev numerical integration. It has been investigated how frequency, waveguide layer thickness, and viscoelastic material loss factor affect phase velocity and Love wave attenuation. The mode-III dynamic stress intensity factor at the left and right crack-tip is investigated for various thicknesses of the waveguide layer and loss factor of viscoelastic material. The outcomes were verified using numerical data from the COMSOL Multiphysics 5.6 FEA software. The findings are fundamental and could be used in the design of particular sensors. [ABSTRACT FROM AUTHOR]

An inverse source problem in the stationary radiative transport in two dimension in an absorbing and scattering medium is considered, where the source is directionally quadratic polynomial. 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 coefficients in the angular variable, we show how to recover the nonlinear anisotropic radiative source from boundary measurements. [ABSTRACT FROM AUTHOR]

This paper studies the inhomogeneous defocusing coupled Schrödinger system i ⁢ u ˙ j + Δ ⁢ u j = | x | - ρ ⁢ (∑ 1 ≤ k ≤ m a j ⁢ k ⁢ | u k | p ) ⁢ | u j | p - 2 ⁢ u j , ρ > 0 , j ∈ [ 1 , m ] . The goal of this work is to prove the scattering of energy global solutions in the conformal space made up of f ∈ H 1 ⁢ (ℝ N) such that x ⁢ f ∈ L 2 ⁢ (ℝ N) . The present paper is a complement of the previous work by the first author and Ghanmi [T. Saanouni and R. Ghanmi, Inhomogeneous coupled non-linear Schrödinger systems, J. Math. Phys. 62 2021, 10, Paper No. 101508]. Indeed, the supplementary assumption x ⁢ u 0 ∈ L 2 enables us to get the scattering in the mass-sub-critical regime p 0 < p ≤ 2 - ρ N + 1 , where p 0 is the Strauss exponent. The proof is based on the decay of global solutions coupled with some non-linear estimates of the source term in Strichartz norms and some standard conformal transformations. Precisely, one gets | t | α ⁢ ∥ u ⁢ (t) ∥ L r ⁢ (ℝ N) ≲ 1 for some α > 0 and a range of Lebesgue norms. The decay rate in the mass super-critical regime is the same one as of e i ⋅ Δ ⁢ u 0 . This rate is different in the mass sub-critical regime, which requires some extra assumptions. The novelty here is the scattering of global solutions in the weighted conformal space for the class of source terms p 0 < p < 2 - ρ N - 2 + 1 . This helps to better understand the asymptotic behavior of the energy solutions. Indeed, the source term has a negligible effect for large time and the above non-linear Schrödinger problem behaves like the associated linear one. In order to avoid a singular source term, one assumes that p ≥ 2 , which restricts the space dimensions to N ≤ 3 . In a paper in progress, the authors treat the same problem in the complementary case ρ < 0 . [ABSTRACT FROM AUTHOR]

The proposed revisit to a classical problem in fluid–structure interaction is due to an interest in the analysis of the narrow resonances corresponding to a low-frequency fluid-borne wave, inspired by modeling and design of metamaterials. In this case, numerical implementations would greatly benefit from preliminary asymptotic predictions. The normal incidence of an acoustic wave is studied for a circular cylindrical shell governed by plane strain equations in elasticity. A novel high-order asymptotic procedure is established considering for the first time all the peculiarities of the low-frequency behavior of a thin fluid-loaded cylinder. The obtained results are exposed in the form suggested by the Resonance Scattering Theory. It is shown that the pressure scattered by rigid cylinder is the best choice for a background component. Simple explicit formulae for resonant frequencies, amplitudes, and widths are presented. They support various important observations, including comparison between widths and the error of the asymptotic expansion for frequencies. [ABSTRACT FROM AUTHOR]

The enhancement of scattered field from cylindrical structures in the presence of SPP waves is analyzed. The SPP waves are excited using the Turbadar-Kretschmann-Raether (TKR) configuration and a cylindrical wave approach (CWA) is implemented to obtain the scattered field. Different arrangements such as a corner reflector and a strip are simulated by means of multiple circular cylinders. It is noted that the back-scattered field from the strip is very strong and can be one of the main challenges in plasmonic communication. Moreover, the simulations give the idea that what combination of structure size and distance from the interface does not produce significant scattering for both the strip and corner reflector. To better understand the phenomenon, and to provide a good insight, two-dimensional near zone field maps are generated to observe field in the vicinity of the object. In the presence of SPP waves, simulations show strong field near the edges like dipole field which is contrary to usual scattering in the absence of SPP waves for a plane wave illumination. [ABSTRACT FROM AUTHOR]

For a better understanding of the physico-chemistry in the interstellar medium, collisional data are needed. In this work, we provide rate coefficients for the recently detected by Cabezas and collaborators in 2023 sodium cyanoacetylide molecule NaC |$_{3}$| N(⁠|$X^{1}\Sigma ^{+}$|⁠) induced by collisions with He. A new two-dimensional potential energy surface (2D-PES) is derived by adopting the high-level theory of the explicitly correlated coupled cluster with single, double, and perturbative triple excitations (CCSD(T)-F12) in conjunction with the aug-cc-pVTZ basis sets. Our 2D-PES presents two minima: the global one with a well depth of |$-86.58$|  cm |$^{-1}$| and the second well with a |$-47.01$|  cm |$^{-1}$| depth. This was expected by the Natural Bond Orbital analysis showing two electrophilic zones located on Na and N linked Carbon with respective atomic charges : |$+0.96575$| and |$+0.28910$|⁠. This PES was used to calculate inelastic cross-sections within the framework of the close-coupling theory for total energies |$\le 170$|  cm |$^{-1}$| and |$J\le 22$|⁠. Using the Maxwell–Boltzmann distribution of kinetic energies, these cross-sections were integrated to generate the collisional (de)-excitation rate coefficients for temperatures below 30 K. In order to estimate the impact of the computed collisional rates, a non-local thermodynamical equilibrium radiative transfer calculation was performed. The new collisional data can allow accurate NaC |$_{3}$| N abundance determination in the interstellar medium. [ABSTRACT FROM AUTHOR]

In this paper, we study long time behavior of solution to the quantum Zakharov system in two dimensions. We construct a small global solution to the quantum Zakharov system which scatters to a given free solution by using space-time resonance method developed by Gustafson-Nakanishi-Tsai [Commun. Contemp. Math. 11 (2009), pp. 657–707] and Germain-Masmoudi-Shatah [Int. Math. Res. Not. IMRN 3 (2009), 414–432; J. Math. Pures Appl. (9) 97 (2012), pp. 505–543] etc. [ABSTRACT FROM AUTHOR]

The scattering of flexural waves in piezoelectric thin plates with defects effects the electro-mechanical coupling property. Theoretical analysis for flexural waves is lack of a suitable decoupling function. Here, we have developed a method based on applied electric field to make a solution of the dynamic moment concentration factor (DMCF) for flexural waves scattering problems. The DMCFs of the piezoelectric materials have been found that it is significantly larger than those of the ordinary elastic materials because of electro-mechanical coupling. In the region of low frequency, DMCFs have a dependence on applied electric field and independent on the incident angle. Those opposite phenomena are observed as the frequency increasing. Those results provide theoretical guidance for dynamic analysis and strength design of piezoelectric material structures. [ABSTRACT FROM AUTHOR]

This review is based on the radar cross-section (RCS) reduction techniques, with the prominence of the metasurface and its design. The thorough detail starts with introducing the concepts of the RCS and its reduction techniques. Then, traditional and recent techniques are provided to reduce RCS, emphasizing the scattering and absorption methods. An in-depth analysis of shaping processes and Radar Absorbing Materials (RAM) is provided, which are two standard RCS reduction techniques. It also thoroughly analyses the metamaterial-based RCS reduction, considering both active and passive configurations. The primary aspects covered regarding the utilization of metasurfaces for reducing RCS include profile, conformality, polarization sensitivity, and design complexity. To provide comparison and evaluation, the review includes tabulated information on performance parameters such as the method used, frequency range, size, optimization method, and planar or conformal design of RCS reduction. Additionally, the paper identifies areas within the field that require further in-depth research and investigation. [ABSTRACT FROM AUTHOR]

Reciprocal scatterers necessarily extinguish the same amount of incoming power when excited from opposite directions. This property implies that it is not possible to realize scatterers that are transparent when excited from one direction but that scatter and absorb light for the opposite excitation, limiting opportunities in the context of asymmetric imaging and nanophotonic circuits. This reciprocity constraint may be overcome with an external bias that breaks time-reversal symmetry, posing however challenges in terms of practical implementations and integration. Here, we explore the use of tailored nonlinearities combined with geometric asymmetries in suitably tailored resonant nanoantennas. We demonstrate that, under suitable design conditions, a nonlinear scatterer can be cloaked for one excitation direction, yet strongly scatters when excited at the same frequency and intensity from the opposite direction. This nonreciprocal scattering phenomenon opens opportunities for nonlinear nanophotonics, asymmetric imaging and visibility, all-optical signal processing and directional sensing. [ABSTRACT FROM AUTHOR]

Recent experimental observation in thermal-induced gelation of silica-based shear thickening fluids (STFs) has necessitated the efforts to address the thermal instability of the STFs. The shear thickening behavior of hydrophilic fumed silica/PEG disappeared after thermal treatment. Hydrophobic surface is demonstrated to enhance thermal stability of the fumed silica/PEG system under the same thermal treatment. Dynamic temperature sweep experiments reveal a temperature-induced sol–gel transition of the hydrophilic silica/PEG. Meanwhile, hydrophobic silica/PEG does not undergo such gelation and still displays viscosity thickening after thermal treatment. This gelation process is found to be concentration-dependent and irreversible, with enhanced gelation at higher specific surface areas of hydrophilic silica particles. The small-angle X-ray scattering (SAXS) studies suggest that this sol–gel transition is likely attributed to the reduction of solvation layer which could be highly influenced by particle surface hydrophilicity. Comprehensive experiments, including Soxhlet extraction and rheology, confirm that the resulting stable three-dimensional structure is not formed by chemical crosslinks but behaves as a physical network. It is demonstrated how tailoring particle–medium interactions through controlling particle surface characteristics can be used to improve thermal stability of silica-based STFs. [ABSTRACT FROM AUTHOR]

Highly concentrated aqueous electrolytes (termed water-in-salt electrolytes, WiSEs) at solid-liquid interfaces are ubiquitous in myriad applications including biological signaling, electrosynthesis, and energy storage. This interface, known as the electrical double layer (EDL), has a different structure in WiSEs than in dilute electrolytes. Here, we investigate how divalent salts [zinc bis(trifluoromethylsulfonyl)imide, Zn(TFSI)2], as well as mixtures of mono-and divalent salts [lithium bis(trifluoromethylsulfonyl) imide (LiTFSI) mixed with Zn(TFSI)2], affect the short-and long-range structure of the EDL under confinement using a multimodal combination of scattering, spectroscopy, and surface forces measurements. Raman spectroscopy of bulk electrolytes suggests that the cation is closely associated with the anion regardless of valency. Wide-angle X-ray scattering reveals that all bulk electrolytes form ion clusters; however, the clusters are suppressed with increasing concentration of the divalent ion. To probe the EDL under confinement, we use a Surface Forces Apparatus and demonstrate that the thickness of the adsorbed layer of ions at the interface grows with increasing divalent ion concentration. Multiple interfacial layers form following this adlayer; their thicknesses appear dependent on anion size, rather than cation. Importantly, all electrolytes exhibit very long electrostatic decay lengths that are insensitive to valency. It is likely that in the WiSE regime, electrostatic screening is mediated by the formation of ion clusters rather than individual well-solvated ions. This work contributes to understanding the structure and charge-neutralization mechanism in this class of electrolytes and the interfacial behavior of mixed-electrolyte systems encountered in electrochemistry and biology. [ABSTRACT FROM AUTHOR]

This work investigates the time asymptotics of the inhomogeneous coupled Schrödinger equations i∂tuj+Δuj=|x|−ρ∑1≤k≤majk|uk|p|uj|p−2uj$$ \mathrm{i}{\partial}_t{u}_j&#x0002B;\Delta {u}_j&#x0003D;{\left&#x0007C;x\right&#x0007C;}&#x0005E;{-\rho}\left(\sum \limits_{1\le k\le m}{a}_{jk}{\left&#x0007C;{u}_k\right&#x0007C;}&#x0005E;p\right){\left&#x0007C;{u}_j\right&#x0007C;}&#x0005E;{p-2}{u}_j $$, where j∈[1,m],ρ>0$$ j\in \left[1,m\right],\rho >0 $$, and uj:ℝt×ℝx3→ℂ$$ {u}_j:{\mathrm{\mathbb{R}}}_t\times {\mathrm{\mathbb{R}}}_x&#x0005E;3\to \mathrm{\mathbb{C}} $$. Here, one treats the energy‐critical regime u(0,·)∈[H1(ℝN)]m$$ u\left(0,\cdotp \right)\in {\left[{H}&#x0005E;1\left({\mathrm{\mathbb{R}}}&#x0005E;N\right)\right]}&#x0005E;m $$ and 1=sc:=N2−2−ρ2(p−1)$$ 1&#x0003D;{s}_c:&#x0003D; \frac{N}{2}-\frac{2-\rho }{2\left(p-1\right)} $$. This is the index of the invariant Sobolev norm under the dilatation ‖λ2−ρ2(p−1)u(λ2t,λ·)‖H˙sc=λμ−N2+2−ρ2(p−1)‖u(λ2t)‖H˙sc$$ {\left\Vert {\lambda}&#x0005E;{\frac{2-\rho }{2\left(p-1\right)}u}\left({\lambda}&#x0005E;2t,\lambda \cdotp \right)\right\Vert}_{{\dot{H}}&#x0005E;{s_c}}&#x0003D;{\lambda}&#x0005E;{\mu -\frac{N}{2}&#x0002B;\frac{2-\rho }{2\left(p-1\right)}}{\left\Vert u\left({\lambda}&#x0005E;2t\right)\right\Vert}_{{\dot{H}}&#x0005E;{s_c}} $$. To the authors knowledge, the technique used in order to prove the scattering of an energy global solution to the above problem in the sub‐critical regime s

Context. The hydrogen deuteride (HD) molecule is an important deuterium tracer in astrophysical studies. The atmospheres of gas giants are dominated by molecular hydrogen, and the simultaneous observation of H2 and HD lines provides reliable information on the D/H ratios on these planets. The reference spectroscopic parameters play a crucial role in such studies. Under the thermodynamic conditions encountered in these atmospheres, spectroscopic studies of HD require not only the knowledge of line intensities and positions but also accurate reference data on pressure-induced line shapes and shifts. Aims. Our aim is to provide accurate collision-induced line-shape parameters for HD lines that cover any thermodynamic conditions relevant to the atmospheres of giant planets, namely any relevant temperature, pressure, and perturbing gas composition (the H2–He mixture). Methods. We performed quantum-scattering calculations on our new, highly accurate ab initio potential energy surface (PES), and we used scattering S matrices obtained in this way to determine the collision-induced line-shape parameters. We used cavity ring-down spectroscopy to validate our theoretical methodology. Results. We report accurate collision-induced line-shape parameters for the pure rotational R(0), R(1), and R(2) lines, the most relevant HD lines for investigations of the atmospheres of the giant planets. Besides the basic Voigt-profile collisional parameters (i.e., the broadening and shift parameters), we also report their speed dependences and the complex Dicke parameter, which can influence the effective width and height of the HD lines up to almost a factor of 2 for giant planet conditions. The sub-percent-level accuracy reached in this work is a considerable improvement over previously available data. All the reported parameters (and their temperature dependences) are consistent with the HITRAN database format, hence allowing for the use of the HITRAN Application Programming Interface (HAPI) for generating the beyond-Voigt spectra of HD. [ABSTRACT FROM AUTHOR]

Context. Small Solar System bodies (SSSBs) hold crucial information for understanding the formation and evolution of the Solar System. However, due to their considerable distance, small size, fast rotation, and a lack of prior information, the detection of these celestial bodies, especially their internal structures, faces numerous challenges. Aims. We explore whether the 3D structure of SSSBs can be reconstructed using monostatic radar. We investigated a more convenient observation mode and addressed the issue of the poor imaging quality of internal structures within existing imaging algorithms. Methods. Our study focused on a high-precision 3D imaging method for the internal structure of SSSBs based on radar signals. First, we considered a flyby observation mode that uses the spinning characteristics of the target for global observations, and we set up a scaled-down experimental system in the laboratory to simulate this observation mode. Next, we constructed a 3D printed physical surface model based on the shape of the asteroid 162173 Ryugu. We filled it with sand and inserted a small bottle containing different materials separately to construct two distinct layered analogs. The analogs were employed in laboratory measurements to acquire radar echoes, which were then inverted using both a classic back-projection (BP) algorithm and a modified multilayer back-projection (MLBP) method. Results. The results shown that the 3D surface structure of the target can be reconstructed well through the BP and MLBP algorithms. The MLBP algorithm exhibits a higher reconstruction accuracy for internal structures. Moreover, compared to the BP method, the MLBP method is less sensitive to the quality of echo signals, resulting in a relatively stable imaging performance. Conclusions. Our findings reveal that observing and reconstructing the high-precision structure of SSSBs is feasible through our proposed method. The observation mode, experimental setup, and analog modeling approach are widely applicable and can be applied in future research on the detection of SSSBs with more diverse and complex structures. [ABSTRACT FROM AUTHOR]

Context. Cold planets, including all habitable planets, produce only scattered light emission in the visual to near-infrared wavelength range. For this reason it is highly desirable to adapt the technique for the direct imaging of reflected light from extra-solar planets. Aims. For the nearby system ε Eri, we want to set much deeper detection limits for the expected scattered radiation from the radial velocity planet candidate (≈0.7 MJ) and the warm dust using the VLT/SPHERE adaptive optics (AO) instrument with the ZIMPOL imaging polarimeter. Methods. We carried out very deep imaging polarimetry of ε Eri based on 38.5 h of integration time with a broad-band filter (λc = 735 nm) for the search of the polarization signal from a planet or from circumstellar dust using AO, coronagraphy, high precision differential polarimetry, and angular differential imaging. The data were collected during 12 nights within four epochs distributed over 14 months and we searched for a signal in the individual epochs. We also combined the full data set to achieve an even higher contrast limit considering the Keplerian motion using the K-Stacker software. All data were also combined for the search of the scattering signal from extended dust clouds. We improved various data reduction and post-processing procedures and also developed new ones to enhance the sensitivity of SPHERE/ZIMPOL further. The final detection limits were quantified and we investigated the potential of SPHERE/ZIMPOL for deeper observations. Results. The data of ε Eridani provide unprecedented contrast limits but no significant detection of a point source or an extended signal from circumstellar dust. For each observing epoch, we achieved a 5 σ풩 point source contrast for the polarized intensity CP = Qϕ/I★ between 2 × 10−8 and 4 × 10−8 at a separation of ρ ≈ 1″, which is as expected for the proposed radial velocity planet at a quadrature phase. The polarimetric contrast limits are close to the photon noise limits for ρ > 0.6″ or about six times to 50 times better than the intensity limits because polarimetric imaging is much more efficient for speckle suppression. Combining the data for the search of a planet moving on a Keplerian orbit with the K-Stacker technique improves the contrast limits further by about a factor of two, when compared to an epoch, to about CP = 0.8 × 10−8 at ρ = 1″. This would allow the detection of a planet with a radius of about 2.5 RJ. Should future astrometry provide strong constraints on the position of the planet, then a 3 σ풩 detection at 1″ with CP ≈ 5 × 10−9 would be within reach of our data. The surface brightness contrast limits achieved for the polarized intensity from an extended scattering region is about 15 mag arcsec−2 at 1″ or up to 3 mag arcsec−2 deeper than previous limits. For ε Eri, these limits exclude the presence of a narrow dust ring and they constrain the dust properties. The photon statistics would allow deeper limits but we find a very weak systematic noise pattern probably introduced by polarimetric calibration errors. Conclusions. This ε Eri study shows that the polarimetric contrast limits for reflecting planets with SPHERE/ZIMPOL can be improved to a level below Cp < 10−8 by just collecting more data during many nights using software such as K-Stacker, which can combine all data considering the expected planet orbit. Contrast limits of Cp ≈ 10−9 are within reach for ε Eri if the search can be optimized for a planet with a well-known orbit. This limit is also attainable for other bright nearby stars, such as α Cen or Sirius A. Such data also provide unprecedented sensitivity for the search of extended polarized emission from warm circumstellar dust. [ABSTRACT FROM AUTHOR]

A large arsenal of space-based and ground-based instruments is dedicated to the observation of radio emissions, whether they originate within our solar system or not. Radio photons interact with anisotropic density fluctuations in the heliosphere which can alter their trajectory and influence the properties that are deduced from observations. This is particularly evident in solar radio observations, where anisotropic scattering leads to highly directional radio emissions. Consequently, observers at varying locations will measure different properties, including different source sizes, source positions, and intensities. However, it is not known whether the measurements of the decay time of solar radio bursts are also affected by the observer's position. Decay times are dominated by scattering effects, and so are frequently used as proxies of the level of density fluctuations in the heliosphere, making the identification of any location-related dependence crucial. We combine multi-vantage observations of interplanetary Type III bursts from four non-collinear, angularly separated spacecraft with simulations to investigate the dependence of the decay- and rise-time measurements on the separation of the observer from the source. We propose a function to characterise the entire time profile of radio signals, allowing for the simultaneous estimation of the peak flux, decay time, and rise time, while demonstrating that the rise phase of radio bursts is non-exponential, having a non-constant growth rate. We determine that the decay and rise times are independent of the observer's position, identifying them as the only properties that remain unaffected and thus do not require corrections for the observer's location. Moreover, we examine the ratio between the rise and decay times and find that it does not depend on the frequency. Therefore, we provide the first evidence that the rise phase is also significantly impacted by scattering effects, adding to our understanding of the plasma emission process. [ABSTRACT FROM AUTHOR]

The role of various light scattering phenomena in aesthetics and clinical practice is explored in this review. Four main types of light scattering, Tyndall, Rayleigh, Mie, and Raman, are discussed. Each type is explained in terms of its physical principles and its applications in aesthetic medicine. Tyndall scattering is relevant in understanding the blue appearance of certain dermal fillers. Rayleigh scattering contributes to skin tone perception and plays a role in certain laser treatments. Mie scattering is important in laser hair removal and the appearance of skin conditions like melasma. Raman scattering, while primarily used in research, shows promise for non‐invasive skin analysis, personalized skincare, treatment monitoring, and early skin cancer detection. It is important to understand these scattering phenomena for optimizing light‐based aesthetic procedures and developing effective treatments. Properly applying the appropriate scattering theory based on relative particle size is crucial in clinical aesthetic practice. [ABSTRACT FROM AUTHOR]

Manipulating the light polarization properties of gold nanoparticle aggregates can facilitate their applications in sensing and imaging. However, control of the intrinsic light polarization on demand at the nanoscale is hindered by the lack of a fundamental understanding of the structure-dependent plasmon coupling in the aggregates. Here, the polarization properties of intrinsic photoluminescence (PL) and scattering of gold nanoparticle dimers and trimers are studied experimentally and computationally at the single-aggregate level. We find that the PL excitation and emission polarization degrees of the aggregates are highly correlated to the shift of their PL and scattering spectra. The results suggest that the degree of PL polarization is dominated by the strength of the longitudinal plasmon resonance mode arising from the plasmon coupling between the two closest particles in the aggregate. While the PL direction is always along the two most strongly interacting particles in the trimers, changing the arrangement can modify the PL polarization degree. This work provides further insights into the mechanism of the plasmon coupling-induced polarized optical response of aggregated metal nanoparticles and suggests routes to achieve on-demand control of the PL light polarization. This paves the way to using the polarized optical response of plasmonic nanostructures for applications in photonics including sensing and imaging. [ABSTRACT FROM AUTHOR]

A method to fit Compton profiles in x‐ray fluorescence (XRF) spectroscopy using a line shape calculated from first principles is proposed. The fitting procedure incorporates the Compton profile calculations and the double Compton scattering line shape algorithm. The results demonstrate the effectiveness of the fitting approach in accurately describing the measured scattering spectra, with good agreement observed between the fit and experimental data. The findings of this study can be used for more accurate characterization of the scattering peaks in XRF spectroscopy. [ABSTRACT FROM AUTHOR]

This work studies the focusing inhomogeneous nonlinear equation of Hartree type і∂tu - Кλu +|х|-τ-|u|p-2)(Jα*|.|-τ|u|P)u = 0, u(t.x): R x R³ → C. Here, the linear Schrödinger operator reads Kλ:= - Δ+ λ/|x|² for some λ > - 1/4. The Riesz potential is Jα (x) = Cα|x|-(3-α) for certain 0 <α< 3. The singular decaying term |x|-τ for some τ > 0 gives an inhomogeneous non-linearity. One considers the inter-critical regime, namely, 1 +2 (1-τ)+α /3 0 because there is no dispersive estimate L¹→ L∞ for λ<0. Contrarily to the homogeneous case τ = 0, for λ> 0, there is a ground state which minimizes the associated Gagliardo-Nirenberg-type estimate. The purpose is to investigate the energy scattering of global solutions under the ground state threshold. One uses the method of Dodson-Murphy based on Tao's scattering criteria and Morawetz estimates. The decay of the inhomogeneous term |x|-τ avoids any spherically symmetric assumption. [ABSTRACT FROM AUTHOR]

• Observation of Multiple layer structures (Temperature Sheets) around the tropopause region and lower stratosphere. • Strong hydrostatic stability responsible for the intensity gradient in the radio refractive index. • Temperature sheets in the troposphere have significant implications for weather and atmospheric stability. • Higher-order spectral analysis has been applied to the atmospheric signals to detect the nonlinearities associated with the temperature sheets near the tropopause region. • Large shear region shows the temperature variation, which results in temperature sheet formation near the tropopause region. Temperature sheets have been observed in the lower stratosphere up to 20 km, with strong (positive) temperature gradients within very thin layers. These were observed from vertical profiles obtained from the Stratosphere and Troposphere (ST) radar located in Kolkata. The sheets tend to occur in groups and contribute to the regions of high static stability, inhibiting vertical air motion. Several experiments were carried out to understand the backscattering mechanism of the Very High Frequency (VHF) radar. Many experiments have reported the multiple layered structures at and around the tropopause regions, especially in the lower stratosphere, it is well established that these layered structures are due to presence of strong negative and positive temperature gradients, which is called as temperature sheets. In order to understand the nonlinearities associated with temperature sheets, Higher-order spectral analysis has been carried out on backscattered signals received from the Mesosphere Stratosphere and Troposphere (MST) radar. This approach allowed for a more detailed examination of the nonlinearities associated with temperature sheets. Therefore, this study proposes a new way of distinctly identifying temperature sheets and the process associated with them using Nonlinear Index based measurements. [ABSTRACT FROM AUTHOR]

Most measurements of the diffuse light of the night sky to date consider only the intensity of the light field, and current models can successfully reproduce these measurements. However, this approach is incomplete as it overlooks the polarization state of the light. Few measurements (and no successful models) of night-sky polarimetry appear in the literature. We present a new model of night-sky polarization that successfully reproduces observations in a heterogeneous environment and for a real distribution of finite-sized light sources over the intermediate region surrounding the observer. The model compares favourably with field measurements made in Slovakia in 2021 May. The results described herein help advance understanding of the angular distributions of artificial light at night from ground sources and the relative contributions of sources to the overall brightness of the night sky. [ABSTRACT FROM AUTHOR]

This study aimed to examine the mechanisms of the photoplethysmography (PPG) signal formation using Monte Carlo simulations of light transport in biological tissues and experimental observations. Based on a three-layer skin model in backscattering geometry, we sequentially simulated volumetric blood changes and the aggregation/disaggregation of erythrocytes in the dermal layer and estimated their contribution to the registered PPG signal. The calculations were conducted for two wavelengths: 525 nm and 810 nm. For green light, absorption predominates over scattering in the formation of a PPG signal, whereas, for near-infrared light, scattering prevails over absorption. This theoretical result was verified using the Modified Beer–Lambert law and clinical in vivo PPG data of seven healthy subjects. Changes in the size of the scatterers during erythrocyte aggregation and disaggregation can significantly contribute to the PPG signal at near-infrared light. Thus, for the green waveband, the classical volumetric model can be considered dominant in the PPG signal formation. In contrast, for the near-infrared range, both volumetric and aggregation effects must be considered as being approximately equal. [ABSTRACT FROM AUTHOR]

We present a theoretical framework for linking quasar properties, such as quasar age, to the surrounding Ly α emission intensity. In particular, we focus on a method for mapping the large-scale structure of Ly α emission intensity with galaxy spectra from wide-field spectroscopic surveys, e.g. the Subaru Prime Focus Spectrograph (PFS) or the Dark Energy Spectroscopic Instrument (DESI), and consider the quasar-induced Ly α emission from the intergalactic medium (IGM). To do this, we construct a theoretical model based on two physical processes: resonant scattering of quasar Ly α photons and fluorescence due to quasar ionizing photons, finding that the fluorescence contribution due to optically thick gas clouds is dominant. Taking into account the light-cone effect and assuming a typical quasar spectrum, we calculate the fluorescence contribution to the spectrum stacked within each bin of the separation angle from the quasar as a function of quasar age. Furthermore, we compute the quasar-Ly α emission cross-correlation and its SNR for the planned PFS survey. The predicted signal can only account for |$\sim 10~{{\ \rm per\ cent}}$| of the measurements indicated from the BOSS and eBOSS surveys in the outer region of |$\gtrsim 10\ \rm {cMpc}\ \rm {h}^{-1}$|⁠ , and the predicted SNR is not sufficient to detect the quasar-induced contribution. However, we found that our model, combined with the contribution of star-forming galaxies, is not in conflict with these measurements. We discuss other possible contributions to the Ly α emission excess around quasars, the efficiency of using spectroscopic fibres, and the redshift dependence of our model. [ABSTRACT FROM AUTHOR]

Volume data encompasses the intricate internal details of objects, offering a canvas for rendering translucent aspects. However, pursuing realistic lighting in volume rendering requires substantial computational resources. We propose a method that capitalizes on the shared scattering patterns found in similar materials, allowing us to create templates that store these patterns for specific materials, facilitating efficient rendering. Derived from material properties, these templates enable the faithful representation of scattered light without imposing a significant computational burden, regardless of the volume data's scale. This approach ensures a clear depiction of material characteristics and light scattering in the resulting images. The swift generation of templates, achievable within 30 milliseconds, empowers real-time adaptation to changes in lighting and materials, making them a valuable asset for exploring data from multiple perspectives. [ABSTRACT FROM AUTHOR]

This research article investigates the effects of object's vibration and fluid movement on the acoustics of subsonic flows, specifically focusing on the scattering of acoustic waves by a vibrating rigid plate submerged in uniform flow. The acoustic plane wave that impacts the plate, coupled with its oscillatory motion, causes a disruption in the fluid medium. This disturbance, in turn, gives rise to a Rayleigh wave that propagates along the boundary separating the plate and the fluid. The study uses the Wiener‐Hopf technique to analytically model the acoustic scattering by a rigid barrier of finite dimensions and analyze the relationship between acoustics and structures. The method involves applying Fourier transformations to the governing boundary value problem and resolving the Wiener‐Hopf equations using the factorization theorem, Liouville's theorem, and analytical continuation. The integral equations of scattered potential computed asymptotically are used to describe the acoustic characteristics of structures and their interaction with fluid flow in subsonic conditions. The findings of the study reveal the sharp peaks of the scattered potential at certain angles with more oscillation in high subsonic flow. Also, increasing the frequency of the vibrating plate increases the amplitude of the scattered potential but is attenuated in mean flow whereas enhancing plate vibrations amplifies the scattered sound, and it is more vibrant in high subsonic flow than mean flow and no fluid flow. This research has applications in noise reduction, aeronautical engineering, and the detection of underwater structures using acoustic waves and micropolar elastic media. [ABSTRACT FROM AUTHOR]

Conventional absorbing, reflective and scattering polarizers are facing various issues, such as severe optical loss, necessary oblique incidence, humidity sensitivity or aging‐caused failure. Subnanowires (SNWs) with polymer‐analogue properties, intrinsic order, and multi‐level interactions attract widespread attention as superior candidates for building blocks of polarizers. Herein, freestanding and flexible liquid crystal (LC)‐SNW films are prepared through a facile directional coating method, not only exhibiting good stability for water and repeated temperature fluctuations, but also showing good polarization performance for visible and near‐infrared (NIR) light, with the polarization degree (P) values of 93%, 84%, and 63% at the wavelengths of 580, 780 and 960 nm. And the average haze achieves 85%. The LC‐SNW films have great potential in applications for polarizers, holographic projection imaging and flexible optical devices. [ABSTRACT FROM AUTHOR]

The H-polarized eigenmodes of dielectric waveguide scattering by a finite system of graphene strips are considered in the THz frequency range. The waveguide has one perfectly electric conducting wall. The solution is based on the singular integral equations with Nystrom discretization. Such an approach is efficient and has guaranteed convergence. Dependences of the scattering characteristics on the frequency and the radiation patterns are presented. We study the properties of periodic graphene strip grating with the same values of the chemical potential on every strip and with different values of the chemical potential on every strip. In the first case, the radiation patterns with relatively high side-lobe level are obtained. In the second case, the side-lobe level is reduced to −20 dB. [ABSTRACT FROM AUTHOR]

Radiation hydrodynamical equations with Compton scattering are generally difficult to solve analytically, and usually examined numerically, even if in the subrelativistic regime. We examine the equations available in the subrelativistic regime of k B T |$/$| (m e c 2) ≲ 0.1, h ν |$/$| (m e c 2) ≲ 0.1, and v |$/$| c ≲ 0.1, where T is the electron temperature, ν the photon frequency, and v the fluid bulk velocity. For simplicity, we ignore the induced scattering terms. We then seek and obtain analytical solutions of frequency-dependent radiative moment equations of a hot plasma with bulk motions for several situations in the subrelativistic regime. For example, in the static case of a plane-parallel atmosphere without bulk motions, where equations involve the generalized Kompaneets equation with subrelativistic corrections, we find the Wien-type solution, which reduces to the usual Milne–Eddington solution in the nonrelativistic limit, as well as the power-law-type one, which has a form of [ h ν |$/$| (k B T)]−4. In the moving case of an accelerating one-dimensional flow with bulk motions, we also find the Wien-type and the power-law-type solutions affected by the bulk Compton effect. Particularly, in the Wien-type solutions, due to the bulk Compton effect, the radiation fields gain momentum from the hot plasma in the low-frequency regime of h ν < 3 k B T , while they lose it in the high-frequency regime of h ν > 3 k B T. [ABSTRACT FROM AUTHOR]

Sound can exert forces on objects of any material and shape. This has made the contactless manipulation of objects by intense ultrasound a fascinating area of research with wide-ranging applications. While much is understood for acoustic forcing of individual objects, sound-mediated interactions among multiple objects at close range gives rise to a rich set of structures and dynamics that are less explored and have been emerging as a frontier for research. We introduce the basic mechanisms giving rise to sound-mediated interactions among rigid as well as deformable particles, focusing on the regime where the particles' size and spacing are much smaller than the sound wavelength. The interplay of secondary acoustic scattering, Bjerknes forces, and micro-streaming is discussed and the role of particle shape is highlighted. Furthermore, we present recent advances in characterizing non-conservative and non-pairwise additive contributions to the particle interactions, along with instabilities and active fluctuations. These excitations emerge at sufficiently strong sound energy density and can act as an effective temperature in otherwise athermal systems. [ABSTRACT FROM AUTHOR]

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The quasi-periodic structure of micro cavities formed under the fiber can be used as a scatterer in medical applications and as a sensitive element of fiber-optic sensors. Mathematical modelling of radiation propagation in an optical fiber with a quasi-periodic structure of micro cavities will make it possible to estimate the distribution of scattered radiation intensity along the quasi-periodic structure, as well as the intensity of reflected and transmitted radiation. This will make it possible to estimate the shape, size and geometry of the micro cavities and their location in the fiber core, providing the most optimal parameters of the scattered light flux. Modelling was carried out in the COMSOL Multiphysics package. A section of SMF-28e single-mode fiber with micro heterogeneities placed in the core was considered and the intensity distribution from the side surface of the fiber depending on the shape and size of the defect was evaluated. The report presents the results of the study with defects of different sizes and types. [ABSTRACT FROM AUTHOR]

In absorption spectroscopy, it is challenging to detect absorption peaks with significant differences in their intensity in a single measurement. We enable high-dynamic-range measurements by dispersing scatterers within a sample to create a broad distribution of path lengths (PLs). The sample is placed within an integrating sphere (IS) to capture all scattered light of various PLs. To address the complexities of PLs inside the IS and the sample, we performed a ray-tracing simulation using the Monte Carlo (MC) method, which estimates the measured absorbance A and PL distribution from the sample's absorption coefficient µa and scattering properties at each wavelength λ. This method was validated using dye solutions with two absorption peaks whose intensity ratio is 95:1, employing polystyrene microspheres (PSs) as scatterers. The results confirmed that both peak shapes were delineated in a single measurement without flattening the high absorption peak. Although the measured peak shapes A(λ) did not align with the actual peak shapes µa(λ), MC enabled the reproduction of µa(λ) from A(λ). Furthermore, the analysis of the PL distribution by MC shows that adding scatterers broadens the distribution and shifts it toward shorter PLs as absorption increases, effectively adjusting it to µa. [ABSTRACT FROM AUTHOR]

Plasmonic metal nanostructures can simultaneously scatter and absorb light, with resonance wavelength and strength depending on their morphology and composition. This work demonstrates that unique dichroic effects and high‐contrast colour‐switching can be achieved by leveraging the resonant scattering and absorption of light by plasmonic nanostructures and the specular reflection of the resulting transmitted light. Using core/shell nanostructures comprising a metal core and a dielectric shell, we show that their spray coating on reflective substrates produces dichroic films that can display colour switching at different viewing angles. The high‐contrast colour switching, high flexibility in designing multicolour patterns, and convenience for large‐scale production promise their wide range of applications, including anticounterfeiting, mechanochromic sensing, colour display, and printing. [ABSTRACT FROM AUTHOR]

Self-healing optical beams are a class of propagation modes that can recover their beam shapes after distortion or partial blockage. This self-healing property makes them attractive for use in applications involving turbid media as they can—in theory—penetrate further into these materials than standard Gaussian beams. In this paper, we characterize the propagation of two different self-healing beams (Bessel and Airy) through a solid scattering material with different scatterer concentrations and find that both beams do recover after scattering for samples below a threshold scatterer concentration. Additionally, we test the applicability of both beam shapes for improved sub-surface spectroscopy in heterogeneous materials using fluorescent particles and find that there is an average fluorescence intensity enhancement of 1.3× using self-healing beams versus a standard Gaussian beam. [ABSTRACT FROM AUTHOR]

The advent of 6G communication systems has enabled, through integrated sensing and communications (ISAC), the vision of the intelligent connection of everything. Since such ISAC systems will be utilizing the sub-6-GHz and millimeter-wave (mm-wave) bands, appropriate hybrid, i.e., sensing and communication channel models, are required for their proper operation. This article first presents a comprehensive survey of channel models used in ISAC applications viewed from different modeling perspectives by identifying the challenges encountered in these modeling approaches. A novel hybrid approach for ISAC channel modeling is then introduced wherein the modeling methodology is partitioned into three elements: targets, clutters, and interferences. The advantage of such a flexible modeling approach using these three elements enhances the proposed model’s ability to effectively deal with the specific sensing and communication operational requirements. Finally, further performance enhancement methods, based upon real-time 3D environment reconstruction techniques as well as artificial intelligence (AI), are proposed and discussed. [ABSTRACT FROM AUTHOR]

Integrated sensing and communication (ISAC) has been defined as one of the major usage scenarios for 6G. When sensing and communication channels coexist in ISAC scenarios, neither conventional communication nor sensing channel models are applicable. As the foundation of ISAC studies, a new channel modeling methodology is required to characterize both sensing and communication channels and their correlations. This article introduces the framework of a general ISAC channel model, which integrates a deterministic multiscattering-center (MSC) model of sensing targets to the stochastic propagation channel model. Parameterizations of the proposed channel model rely on channel measurements. This article introduces two ISAC channel measurement methodologies based on the vector network analyzer (VNA) and a novel dual-sensor measurement system. The proposed methods can be applied in future 6G ISAC channel model standardization and system evaluations. [ABSTRACT FROM AUTHOR]

This article studies the mathematical modeling of an acoustic field, which is scattered by a homogeneous isotropic cylinder with a radially inhomogeneous elastic coating. The primary perturbation field is a cylindrical harmonic sound wave emitted by a linear source. It is assumed that the axes of the source and scatterer are not parallel and do not lie in the same plane. The density and elastic moduli of the coating material are described by continuous functions of the radial coordinate. The results of the calculations of the angular characteristics of the scattered acoustic field in the far zone for different positions of the linear source are presented. [ABSTRACT FROM AUTHOR]

The interdomain electron transfer (IET) between the catalytic flavodehydrogenase domain and the electron-transferring cytochrome domain of cellobiose dehydrogenase (CDH) plays an essential role in biocatalysis, biosensors and biofuel cells, as well as in its natural function as an auxiliary enzyme of lytic polysaccharide monooxygenase. We investigated the mobility of the cytochrome and dehydrogenase domains of CDH, which is hypothesised to limit IET in solution by small angle X-ray scattering (SAXS). CDH from Myriococcum thermophilum (syn. Crassicarpon hotsonii, syn. Thermothelomyces myriococcoides) was probed by SAXS to study the CDH mobility at different pH and in the presence of divalent cations. By comparison of the experimental SAXS data, using pair-distance distribution functions and Kratky plots, we show an increase in CDH mobility at higher pH, indicating alterations of domain mobility. To further visualise CDH movement in solution, we performed SAXS-based multistate modelling. Glycan structures present on CDH partially masked the resulting SAXS shapes, we diminished these effects by deglycosylation and studied the effect of glycoforms by modelling. The modelling shows that with increasing pH, the cytochrome domain adopts a more flexible state with significant separation from the dehydrogenase domain. On the contrary, the presence of calcium ions decreases the mobility of the cytochrome domain. Experimental SAXS data, multistate modelling and previously reported kinetic data show how pH and divalent ions impact the closed state necessary for the IET governed by the movement of the CDH cytochrome domain.

This review is based on the radar cross-section (RCS) reduction techniques, with the prominence of the metasurface and its design. The thorough detail starts with introducing the concepts of the RCS and its reduction techniques. Then, traditional and recent techniques are provided to reduce RCS, emphasizing the scattering and absorption methods. An in-depth analysis of shaping processes and Radar Absorbing Materials (RAM) is provided, which are two standard RCS reduction techniques. It also thoroughly analyses the metamaterial-based RCS reduction, considering both active and passive configurations. The primary aspects covered regarding the utilization of metasurfaces for reducing RCS include profile, conformality, polarization sensitivity, and design complexity. To provide comparison and evaluation, the review includes tabulated information on performance parameters such as the method used, frequency range, size, optimization method, and planar or conformal design of RCS reduction. Additionally, the paper identifies areas within the field that require further in-depth research and investigation.

This study utilizes 3D numerical models to simulate seismic resonances in a volcanic edifice, arising from the interaction between an externally excited wavefield and a magma chamber-conduit system. The magma chamber and conduit efficiently capture the incident wavefield of both P- and S-waves, excited by a high-frequency (~10 Hz) earthquake located within the edifice. Due to multiple internal reflections off the boundaries of the chamber and conduit, prolonged reverberations occur, which are guided along the conduit. Temporal and spectral analyses of synthetic seismograms illustrate that models with larger chambers and wider conduits consistently yield larger resonance amplitudes at distinct frequencies. Our models indicate that a larger magma chamber can produce an intensified scattered wavefield with a broad frequency range, observable up to several hundred meters away from the central conduit. Generally, these externally initiated ‘calabash resonances’ may appear as tremor-like signals at seismometers on the edifice, accompanying more conventional seismic events in its proximity.

Self-healing optical beams are a class of propagation modes that can recover their beam shapes after distortion or partial blockage. This self-healing property makes them attractive for use in applications involving turbid media as they can—in theory—penetrate further into these materials than standard Gaussian beams. In this paper, we characterize the propagation of two different self-healing beams (Bessel and Airy) through a solid scattering material with different scatterer concentrations and find that both beams do recover after scattering for samples below a threshold scatterer concentration. Additionally, we test the applicability of both beam shapes for improved sub-surface spectroscopy in heterogeneous materials using fluorescent particles and find that there is an average fluorescence intensity enhancement of 1.3× using self-healing beams versus a standard Gaussian beam.