Anomalous transparency of water-air interface for low-frequency sound

Sound transmission through water-air interface is normally weak because of a strong mass density contrast. Here we show that the transparency of the interface increases dramatically at low frequencies. Rather counterintuitively, almost all acoustic energy emitted by a sufficiently shallow monopole source under water is predicted to be radiated into atmosphere. Physically, increased transparency at lower frequencies is due to the increasing role of inhomogeneous waves and a destructive interference of direct and surface-reflected waves under water. The phenomenon of anomalous transparency has significant implications for acoustic communication across the water-air interface, generation of ambient noise, and detection of underwater explosions.Comment: 29 pages, including 4 figure

Surface plasmon resonance study of the actin-myosin sarcomeric complex and tubulin dimers

Biosensors based on the principle of surface plasmon resonance (SPR) detection were used to measure biomolecular interactions in sarcomeres and changes of the dielectric constant of tubulin samples with varying concentration. At SPR, photons of laser light efficiently excite surface plasmons propagating along a metal (gold) film. This resonance manifests itself as a sharp minimum in the reflection of the incident laser light and occurs at a characteristic angle. The dependence of the SPR angle on the dielectric permittivity of the sample medium adjacent to the gold film allows the monitoring of molecular interactions at the surface. We present results of measurements of cross-bridge attachment/detachment within intact mouse heart muscle sarcomeres and measurements on bovine tubulin molecules pertinent to cytoskeletal signal transduction models.Comment: Submitted to Journal of Modern Optics *Corresponding author: Andreas Mershin ([email protected]

Influence of positional correlations on the propagation of waves in a complex medium with polydisperse resonant scatterers

We present experimental results on a model system for studying wave propagation in a complex medium exhibiting low frequency resonances. These experiments enable us to investigate a fundamental question that is relevant for many materials, such as metamaterials, where low-frequency scattering resonances strongly influence the effective medium properties. This question concerns the effect of correlations in the positions of the scatterers on the coupling between their resonances, and hence on wave transport through the medium. To examine this question experimentally, we measure the effective medium wave number of acoustic waves in a sample made of bubbles embedded in an elastic matrix over a frequency range that includes the resonance frequency of the bubbles. The effective medium is highly dispersive, showing peaks in the attenuation and the phase velocity as functions of the frequency, which cannot be accurately described using the Independent Scattering Approximation (ISA). This discrepancy may be explained by the effects of the positional correlations of the scatterers, which we show to be dependent on the size of the scatterers. We propose a self-consistent approach for taking this "polydisperse correlation" into account and show that our model better describes the experimental results than the ISA

Ray-based description of normal mode amplitudes in a range-dependent waveguide

An analogue of the geometrical optics for description of the modal structure of a wave field in a range-dependent waveguide is considered. In the scope of this approach the mode amplitude is expressed through solutions of the ray equations. This analytical description accounts for mode coupling and remains valid in a nonadiabatic environment. It has been used to investigate the applicability condition of the adiabatic approximation. An applicability criterion is formulated as a restriction on variations of the action variable of the ray.Comment: 11 pages, 5 figure

Combining airborne gas and aerosol measurements with HYSPLIT: a visualization tool for simultaneous evaluation of air mass history and back trajectory consistency

The history of air masses is often investigated using backward trajectories to gain knowledge about processes along the air parcel path as well as possible source regions. Here, we describe a refined approach that incorporates airborne gas, aerosol, and environmental data into back trajectories and show how this technique allows for simultaneous evaluation of air mass history and back trajectory reliability without the need to calculate trajectory errors. <br><br> We use the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and add a simple semi-automated computing routine to facilitate high-frequency coverage of back trajectories initiated along free tropospheric (FT) flight tracks and profiles every 10 s. We integrate our in situ physiochemical data by color-coding each of these trajectories with its corresponding in situ tracer values measured at the back trajectory start points along the flight path. The unique color for each trajectory aids assessment of trajectory reliability through the visual clustering of air mass pathways of similar coloration. Moreover, marked changes in trajectories associated with marked changes evident in measured physiochemical or thermodynamic properties of an air mass add credence to trajectories. This is particularly true when these air mass properties are linked to trajectory features characteristic of recognized sources or processes. This visual clustering of air mass pathways is of particular value for large-scale 3-D flight tracks common to aircraft experiments where air mass features of interest are often spatially distributed and temporally separated. <br><br> The cluster-visualization tool used here reveals that most FT back trajectories with pollution signatures measured in the central equatorial Pacific reach back to sources on the South American continent over 10 000 km away and 12 days back in time, e.g., the Amazonian basin. We also demonstrate the distinctions in air mass properties between these and trajectories that penetrate deep convection in the Inter-Tropical Convergence Zone. Additionally, for the first time we show consistency of modeled precipitation along back trajectories with scavenging signatures in the aerosol measured for these trajectories

Modelling Quantum Mechanics by the Quantumlike Description of the Electric Signal Propagation in Transmission Lines

It is shown that the transmission line technology can be suitably used for simulating quantum mechanics. Using manageable and at the same time non-expensive technology, several quantum mechanical problems can be simulated for significant tutorial purposes. The electric signal envelope propagation through the line is governed by a Schrodinger-like equation for a complex function, representing the low-frequency component of the signal, In this preliminary analysis, we consider two classical examples, i.e. the Frank-Condon principle and the Ramsauer effect

Enhanced transmission band in periodic media with loss modulation

Copyright (2014) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in: Applied Physics Letters 105, 204104 (2014); doi: 10.1063/1.4902387 and may be found at: http://dx.doi.org/10.1063/1.490238.We study the propagation of waves in a periodic array of absorbing layers. We report an anomalous increase of wave transmission through the structure related to a decrease of the absorption around the Bragg frequencies. The effect is first discussed in terms of a generic coupled wave model extended to include losses, and its predictions can be applied to different types of waves propagating in media with periodic modulation of the losses at the wavelength scale. The particular case of sound waves in an array of porous layers embedded in air is considered. An experiment designed to test the predictions demonstrates the existence of the enhanced transmission band. (C) 2014 AIP Publishing LLC.The work was supported by Spanish Ministry of Science and Innovation and European Union FEDER through Projects FIS2011-29731-C02-01 and -02, also MAT2009-09438. A.M.Y. would like to thank the Erasmus Mundus Project (WELCOME program) for supporting him. V.R.G. acknowledges financial support from the "Pays-de-la-Loire" through the post-doctoral program.Cebrecos Ruiz, A.; Picó Vila, R.; Romero García, V.; Yasser, AM.; Maigyte, L.; Herrero, R.; Botey, M.... (2014). Enhanced transmission band in periodic media with loss modulation. Applied Physics Letters. 105(20):204104-1-204104-4. doi:10.1063/1.4902387S204104-1204104-410520Figotin, A., & Vitebskiy, I. (2008). Absorption suppression in photonic crystals. Physical Review B, 77(10). doi:10.1103/physrevb.77.104421Figotin, A., & Vitebskiy, I. (2010). Magnetic Faraday rotation in lossy photonic structures. Waves in Random and Complex Media, 20(2), 298-318. doi:10.1080/17455030.2010.482575Erokhin, S. G., Lisyansky, A. A., Merzlikin, A. M., Vinogradov, A. P., & Granovsky, A. B. (2008). Photonic crystals built on contrast in attenuation. Physical Review B, 77(23). doi:10.1103/physrevb.77.233102Kumar, N., Botey, M., Herrero, R., Loiko, Y., & Staliunas, K. (2012). High-directional wave propagation in periodic loss modulated materials. Photonics and Nanostructures - Fundamentals and Applications, 10(4), 644-650. doi:10.1016/j.photonics.2012.06.003Staliunas, K., Herrero, R., & Vilaseca, R. (2009). Subdiffraction and spatial filtering due to periodic spatial modulation of the gain-loss profile. Physical Review A, 80(1). doi:10.1103/physreva.80.013821Kumar, N., Herrero, R., Botey, M., & Staliunas, K. (2013). Flat lensing by periodic loss-modulated materials. Journal of the Optical Society of America B, 30(10), 2684. doi:10.1364/josab.30.002684Psarobas, I. E. (2001). Viscoelastic response of sonic band-gap materials. Physical Review B, 64(1). doi:10.1103/physrevb.64.012303Lee, C.-Y., Leamy, M. J., & Nadler, J. H. (2010). Frequency band structure and absorption predictions for multi-periodic acoustic composites. Journal of Sound and Vibration, 329(10), 1809-1822. doi:10.1016/j.jsv.2009.11.030Laude, V., Escalante, J. M., & Martínez, A. (2013). Effect of loss on the dispersion relation of photonic and phononic crystals. Physical Review B, 88(22). doi:10.1103/physrevb.88.224302Hwan Oh, J., Jae Kim, Y., & Young Kim, Y. (2013). Wave attenuation and dissipation mechanisms in viscoelastic phononic crystals. Journal of Applied Physics, 113(10), 106101. doi:10.1063/1.4795285Hussein, M. I. (2009). Theory of damped Bloch waves in elastic media. Physical Review B, 80(21). doi:10.1103/physrevb.80.212301Andreassen, E., & Jensen, J. S. (2013). Analysis of Phononic Bandgap Structures With Dissipation. Journal of Vibration and Acoustics, 135(4). doi:10.1115/1.4023901Allard, J. F., & Atalla, N. (2009). Propagation of Sound in Porous Media. doi:10.1002/9780470747339Tournat, V., Pagneux, V., Lafarge, D., & Jaouen, L. (2004). Multiple scattering of acoustic waves and porous absorbing media. Physical Review E, 70(2). doi:10.1103/physreve.70.026609Umnova, O., Attenborough, K., & Linton, C. M. (2006). Effects of porous covering on sound attenuation by periodic arrays of cylinders. The Journal of the Acoustical Society of America, 119(1), 278-284. doi:10.1121/1.2133715Romero-García, V., Sánchez-Pérez, J. V., & Garcia-Raffi, L. M. (2010). Evanescent modes in sonic crystals: Complex dispersion relation and supercell approximation. Journal of Applied Physics, 108(4), 044907. doi:10.1063/1.3466988Christensen, J., Romero-García, V., Picó, R., Cebrecos, A., de Abajo, F. J. G., Mortensen, N. A., … Sánchez-Morcillo, V. J. (2014). Extraordinary absorption of sound in porous lamella-crystals. Scientific Reports, 4(1). doi:10.1038/srep04674Kogelnik, H., & Shank, C. V. (1972). Coupled‐Wave Theory of Distributed Feedback Lasers. Journal of Applied Physics, 43(5), 2327-2335. doi:10.1063/1.166149

A complex ray-tracing tool for high-frequency mean-field flow interaction effects in jets

This paper presents a complex ray-tracing tool for the calculation of high-frequency Green’s functions in 3D mean field jet flows. For a generic problem, the ray solution suffers from three main deficiencies: multiplicity of solutions, singularities at caustics, and the determining of complex solutions. The purpose of this paper is to generalize, combine and apply existing stationary media methods to moving media scenarios. Multiplicities are dealt with using an equivalent two-point boundary-value problem, whilst non-uniformities at caustics are corrected using diffraction catastrophes. Complex rays are found using a combination of imaginary perturbations, an assumption of caustic stability, and analytic continuation of the receiver curve. To demonstrate this method, the ray tool is compared against a high-frequency modal solution of Lilley’s equation for an off-axis point source. This solution is representative of high-frequency source positions in real jets and is rich in caustic structures. A full utilization of the ray tool is shown to provide excellent results<br/

Aerogel-based metasurfaces for perfect acoustic energy absorption

[EN] The unusual viscoelastic properties of silica aerogel plates are efficiently used to design subwavelength perfect sound absorbers. We theoretically, numerically and experimentally report a perfect absorbing metamaterial panel made of periodically arranged resonant building blocks consisting of a slit loaded by a clamped aerogel plate backed by a closed cavity. The impedance matching condition is analyzed using the Argand diagram of the reflection coefficient, i.e., the trajectory of the reflection coefficient as a function of frequency in the complex plane. The lack or excess of losses in the system can be identified via this Argrand diagram in order to achieve the impedance matching condition. The universality of this tool can be further exploited to design more complex metasurfaces for perfect sound absorption, thus allowing the rapid design of novel and efficient absorbing metamaterials.This work was funded by the RFI Le Mans Acoustique, Region Pays de la Loire. This article is based upon work from COST Action DENORMS CA15125, supported by COST (European Cooperation in Science and Technology). N.J. acknowledges financial support from Generalitat Valenciana through Grant No. APOSTD/2017/042. J.-P.G and V.R.G. gratefully acknowledge the ANR-RGC METARoom (No. ANR-18-CE08-0021) project and the HYPERMETA project funded under the program Etoiles Montantes of the Region Pays de la Loire. J.S-D. acknowledges the support of the Ministerio de Economia y Competitividad of the Spanish government and the European Union FEDER through Project No. TEC2014-53088-C3-1-RFernandez-Marin, AA.; Jimenez, N.; Groby, J.; Sánchez-Dehesa Moreno-Cid, J.; Romero García, V. (2019). Aerogel-based metasurfaces for perfect acoustic energy absorption. Applied Physics Letters. 115(6):061901-1-061901-5. https://doi.org/10.1063/1.5109084S061901-1061901-51156Gesser, H. D., & Goswami, P. C. (1989). Aerogels and related porous materials. Chemical Reviews, 89(4), 765-788. doi:10.1021/cr00094a003Herrmann, G., Iden, R., Mielke, M., Teich, F., & Ziegler, B. (1995). On the way to commercial production of silica aerogel. Journal of Non-Crystalline Solids, 186, 380-387. doi:10.1016/0022-3093(95)90076-4Fricke, J., Lu, X., Wang, P., Büttner, D., & Heinemann, U. (1992). Optimization of monolithic silica aerogel insulants. International Journal of Heat and Mass Transfer, 35(9), 2305-2309. doi:10.1016/0017-9310(92)90073-2Gerlach, R., Kraus, O., Fricke, J., Eccardt, P.-C., Kroemer, N., & Magori, V. (1992). Modified SiO2 aerogels as acoustic impedance matching layers in ultrasonic devices. Journal of Non-Crystalline Solids, 145, 227-232. doi:10.1016/s0022-3093(05)80461-2Gibiat, V., Lefeuvre, O., Woignier, T., Pelous, J., & Phalippou, J. (1995). Acoustic properties and potential applications of silica aerogels. Journal of Non-Crystalline Solids, 186, 244-255. doi:10.1016/0022-3093(95)00049-6Ma, G., Yang, M., Xiao, S., Yang, Z., & Sheng, P. (2014). Acoustic metasurface with hybrid resonances. Nature Materials, 13(9), 873-878. doi:10.1038/nmat3994Yang, M., Meng, C., Fu, C., Li, Y., Yang, Z., & Sheng, P. (2015). Subwavelength total acoustic absorption with degenerate resonators. Applied Physics Letters, 107(10), 104104. doi:10.1063/1.4930944Romero-García, V., Theocharis, G., Richoux, O., Merkel, A., Tournat, V., & Pagneux, V. (2016). Perfect and broadband acoustic absorption by critically coupled sub-wavelength resonators. Scientific Reports, 6(1). doi:10.1038/srep19519Li, Y., & Assouar, B. M. (2016). Acoustic metasurface-based perfect absorber with deep subwavelength thickness. Applied Physics Letters, 108(6), 063502. doi:10.1063/1.4941338Jiménez, N., Huang, W., Romero-García, V., Pagneux, V., & Groby, J.-P. (2016). Ultra-thin metamaterial for perfect and quasi-omnidirectional sound absorption. Applied Physics Letters, 109(12), 121902. doi:10.1063/1.4962328Peng, X., Ji, J., & Jing, Y. (2018). Composite honeycomb metasurface panel for broadband sound absorption. The Journal of the Acoustical Society of America, 144(4), EL255-EL261. doi:10.1121/1.5055847Yang, M., Ma, G., Yang, Z., & Sheng, P. (2013). Coupled Membranes with Doubly Negative Mass Density and Bulk Modulus. Physical Review Letters, 110(13). doi:10.1103/physrevlett.110.134301Yang, Z., Mei, J., Yang, M., Chan, N. H., & Sheng, P. (2008). Membrane-Type Acoustic Metamaterial with Negative Dynamic Mass. Physical Review Letters, 101(20). doi:10.1103/physrevlett.101.204301Lee, S. H., Park, C. M., Seo, Y. M., Wang, Z. G., & Kim, C. K. (2010). Composite Acoustic Medium with Simultaneously Negative Density and Modulus. Physical Review Letters, 104(5). doi:10.1103/physrevlett.104.054301Zhang, J., Romero-García, V., Theocharis, G., Richoux, O., Achilleos, V., & Frantzeskakis, D. (2016). Second-Harmonic Generation in Membrane-Type Nonlinear Acoustic Metamaterials. Crystals, 6(8), 86. doi:10.3390/cryst6080086Zhang, J., Romero-García, V., Theocharis, G., Richoux, O., Achilleos, V., & Frantzeskakis, D. J. (2017). Bright and gap solitons in membrane-type acoustic metamaterials. Physical Review E, 96(2). doi:10.1103/physreve.96.022214Stinson, M. R. (1991). The propagation of plane sound waves in narrow and wide circular tubes, and generalization to uniform tubes of arbitrary cross‐sectional shape. The Journal of the Acoustical Society of America, 89(2), 550-558. doi:10.1121/1.400379Kergomard, J., & Garcia, A. (1987). Simple discontinuities in acoustic waveguides at low frequencies: Critical analysis and formulae. Journal of Sound and Vibration, 114(3), 465-479. doi:10.1016/s0022-460x(87)80017-2M. J. Powell , in Numerical Analysis ( Springer, 1978) pp. 144–157.Groby, J.-P., Huang, W., Lardeau, A., & Aurégan, Y. (2015). The use of slow waves to design simple sound absorbing materials. Journal of Applied Physics, 117(12), 124903. doi:10.1063/1.4915115Jiménez, N., Groby, J.-P., Pagneux, V., & Romero-García, V. (2017). Iridescent Perfect Absorption in Critically-Coupled Acoustic Metamaterials Using the Transfer Matrix Method. Applied Sciences, 7(6), 618. doi:10.3390/app706061

First πK\pi K atom lifetime and πK\pi K scattering length measurements

The results of a search for hydrogen-like atoms consisting of $\pi^{\mp}K^{\pm}$ mesons are presented. Evidence for $\pi K$ atom production by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen in terms of characteristic $\pi K$ pairs from their breakup in the same target ($178 \pm 49$) and from Coulomb final state interaction ($653 \pm 42$). Using these results the analysis yields a first value for the $\pi K$ atom lifetime of $\tau=(2.5_{-1.8}^{+3.0})$ fs and a first model-independent measurement of the S-wave isospin-odd $\pi K$ scattering length $\left|a_0^-\right|=\frac{1}{3}\left|a_{1/2}-a_{3/2}\right|= \left(0.11_{-0.04}^{+0.09} \right)M_{\pi}^{-1}$ ($a_I$ for isospin $I$).Comment: 14 pages, 8 figure