The mechanics of shallow magma reservoir outgassing

Magma degassing fundamentally controls the Earth's volatile cycles. The large amount of gas expelled into the atmosphere during volcanic eruptions (i.e. volcanic outgassing) is the most obvious display of magmatic volatile release. However, owing to the large intrusive:extrusive ratio, and considering the paucity of volatiles left in intrusive rocks after final solidification, volcanic outgassing likely constitutes only a small fraction of the overall mass of magmatic volatiles released to the Earth's surface. Therefore, as most magmas stall on their way to the surface, outgassing of uneruptible, crystal-rich magma storage regions will play a dominant role in closing the balance of volatile element cycling between the mantle and the surface. We use a numerical approach to study the migration of a magmatic volatile phase (MVP) in crystal-rich magma bodies (“mush zones”) at the pore-scale. Our results suggest that buoyancy driven outgassing is efficient over crystal volume fractions between 0.4 and 0.7 (for mm-sized crystals). We parameterize our pore-scale results for MVP migration in a thermo-mechanical magma reservoir model to study outgassing under dynamical conditions where cooling controls the evolution of the proportion of crystal, gas and melt phases and to investigate the role of the reservoir size and the temperature-dependent visco-elastic response of the crust on outgassing efficiency. We find that buoyancy-driven outgassing allows for a maximum of 40-50% volatiles to leave the reservoir over the 0.4-0.7 crystal volume fractions, implying that a significant amount of outgassing must occur at high crystal content (>0.7) through veining and/or capillary fracturing

MULTIPASS: gestion des consentements pour accéder aux données des exploitations dans une chaîne de confiance afin de favoriser l'émergence de nouveaux services pour les agriculteurs

12th EFITA International Conference, Rhode island, GRC, 27-/06/2019 - 29/06/2019International audienceWith the emergence of digital technologies, farms become a relevant source of data to meet the challenges of multi-performance agriculture. Beyond the services provided, access to farmers' data depends on a clear understanding of their use, which must be done in a transparent way. Several codes of conduct at a national or international level push for a voluntary commitment to respect some good practices in the use of agricultural data. To provide a tool and answer farmer's questions on the control of their data and the transparency of the data processing, the partners of the MULTIPASS project, have imagined an interoperable ecosystem of farmer consents management, protecting farmers from no consented uses of their data.Farmers' expectations of such an ecosystem have been expressed during workshops. They want to better identify existing data flows, including actors, data processes, and data clusters. Based on the farmers' expectations, the MULTIPASS project stakeholders have proposed the architecture of an ecosystem integrating two consent management tools as "pilots". This ecosystem should take in charge the interoperability between each consent management tools or with future tools. This solution is based on a shared typology of data and data processes as well as on the specifications of the consent message content. All these elements should be easily accessible to meet the interoperability need of the ecosystem. It is also based on a router, which provides unified access to consent management tools (using API). In particular, it provides the farmer (beneficiary) with an exhaustive view of his/her consents (which can be distributed on several consent management systems), meeting farmers' expectations for transparency. It is also the point where a data provider can check whether the consent required to provide data exists, without needing to know which consent management system is concerned. In this project, the stakeholders want to demonstrate to agricultural professional organizations the benefits and feasibility of a consent management ecosystem. By strengthening the confidence of farmers to share data, the project will allow the emergence of new knowledge and new services

Acoustic metamaterial for low frequency sound absorption in linear and nonlinear regimes

Acoustic metamaterial absorbers have been built and tested with focus on low frequency airborne sound absorption in linear and nonlinear regimes. The absorbers are made up of a series of piled up flat cavities, separated by thin walls and traversed by a perforation at their centre. A model for absorber effective properties is developed and compared with experimental data. The model is used to derive simple formulae for the frequency and the peak value of the absorption coefficient at the lowest frequency resonance, depending on the geometrical parameters of the structure. Different absorbers have been built with several cavity thicknesses to allow comprehensive comparisons with the model. Nonlinear properties of the absorbers are investigated experimentally using sine wave excitation around the resonance frequency with the amplitude of the incident wave up to 250 Pa. Flow resistivity measurements at low flow rates show that the periodic set of cavities does not modify resistivity significantly when compared to a simple perforated cylinder with same thickness. As flow rate increases, the flow resistivity grows linearly according to Forchheimer's law and has a significant dependence on the absorber thickness. A numerical model is developed accounting for the linear growth of flow resistivity with particle velocity amplitude in the central perforation and compared with the measurements at high amplitudes of the incident wave

CATKE: a turbulent-kinetic-energy-based parameterization for ocean microturbulence with dynamic convective adjustment

We describe CATKE, a parameterization for ocean microturbulence with scales between 1 and 100 meters. CATKE is a one-equation model that predicts diffusive turbulent vertical fluxes a prognostic turbulent kinetic energy (TKE) and a diagnostic mixing length that features a dynamic model for convective adjustment (CA). With its convective mixing length, CATKE predicts not just the depth range where microturbulence acts but also the timescale over which mixing occurs, an important aspect of turbulent convection not captured by convective adjustment schemes. As a result, CATKE can describe the competition between convection and other processes such as baroclinic restractification or biogeochemical production-destruction. We estimate CATKE's free parameters with a posteriori calibration to eighteen large eddy simulations of the ocean surface boundary layer, and validate CATKE against twelve additional large eddy simulations with stronger and weaker forcing than used during calibration. We find that a CATKE-parameterized single column model accurately predicts the depth structure of buoyancy and momentum at vertical resolutions between 2 and 16 meters and with time steps of 10-20 minutes. We propose directions for future model development, and future efforts to recalibrate CATKE's parameters against more comprehensive and realistic datasets.Comment: submitted to J. Adv. Model. Earth Sy., 24 pages, 8 figure

Gut microbiota analysis reveals a marked shift to bifidobacteria by a starter infant formula containing a synbiotic of bovine milk-derived oligosaccharides and Bifidobacterium animalis subsp. lactis CNCM I-3446.

Non-digestible milk oligosaccharides were proposed as receptor decoys for pathogens and as nutrients for beneficial gut commensals like bifidobacteria. Bovine milk contains oligosaccharides, some of which are structurally identical or similar to those found in human milk. In a controlled, randomized double-blinded clinical trial we tested the effect of feeding a formula supplemented with a mixture of bovine milk-derived oligosaccharides (BMOS) generated from whey permeate, containing galacto-oligosaccharides and 3'- and 6'-sialyllactose, and the probiotic Bifidobacterium animalis subsp. lactis (B. lactis) strain CNCM I-3446. Breastfed infants served as reference group. Compared with a non-supplemented control formula, the test formula showed a similar tolerability and supported a similar growth in healthy newborns followed for 12 weeks. The control, but not the test group, differed from the breast-fed reference group by a higher faecal pH and a significantly higher diversity of the faecal microbiota. In the test group the probiotic B. lactis increased by 100-fold in the stool and was detected in all supplemented infants. BMOS stimulated a marked shift to a bifidobacterium-dominated faecal microbiota via increases in endogenous bifidobacteria (B. longum, B. breve, B. bifidum, B. pseudocatenulatum)

Metadiffusers : deep-subwavelength sound diffusers

We present deep-subwavelength diffusing surfaces based on acoustic metamaterials, namely metadiffusers. These sound diffusers are rigidly backed slotted panels, with each slit being loaded by an array of Helmholtz resonators. Strong dispersion is produced in the slits and slow sound conditions are induced. Thus, the effective thickness of the panel is lengthened introducing its quarter wavelength resonance in the deep-subwavelength regime. By tuning the geometry of the metamaterial, the reflection coefficient of the panel can be tailored to obtain either a custom reflection phase, moderate or even perfect absorption. Using these concepts, we present ultra-thin diffusers where the geometry of the metadiffuser has been tuned to obtain surfaces with spatially dependent reflection coefficients having uniform magnitude Fourier transforms. Various designs are presented where, quadratic residue, primitive root and ternary sequence diffusers are mimicked by metadiffusers whose thickness are 1/46 to 1/20 times the design wavelength, i.e., between about a twentieth and a tenth of the thickness of traditional designs. Finally, a broadband metadiffuser panel of 3 cm thick was designed using optimization methods for frequencies ranging from 250 Hz to 2 kHz

Rainbow-trapping absorbers: Broadband, perfect and asymmetric sound absorption by subwavelength panels for transmission problems

[EN] Perfect, broadband and asymmetric sound absorption is theoretically, numerically and experimentally reported by using subwavelength thickness panels in a transmission problem. The panels are composed of a periodic array of varying crosssection waveguides, each of them being loaded by Helmholtz resonators (HRs) with graded dimensions. The low cut-off frequency of the absorption band is fixed by the resonance frequency of the deepest HR, that reduces drastically the transmission. The preceding HR is designed with a slightly higher resonance frequency with a geometry that allows the impedance matching to the surrounding medium. Therefore, reflection vanishes and the structure is critically coupled. This results in perfect sound absorption at a single frequency. We report perfect absorption at 300¿Hz for a structure whose thickness is 40 times smaller than the wavelength. Moreover, this process is repeated by adding HRs to the waveguide, each of them with a higher resonance frequency than the preceding one. Using this frequency cascade effect, we report quasi-perfect sound absorption over almost two frequency octaves ranging from 300 to 1000¿Hz for a panel composed of 9 resonators with a total thickness of 11¿cm, i.e., 10 times smaller than the wavelength at 300¿Hz.The authors acknowledge fnancial support from the Metaudible Project No. ANR-13-BS09-0003, cofunded by ANR and FRAE.Jimenez, N.; Romero García, V.; Pagneux, V.; Groby, J. (2017). Rainbow-trapping absorbers: Broadband, perfect and asymmetric sound absorption by subwavelength panels for transmission problems. Scientific Reports. 7(1). doi:10.1038/s41598-017-13706-4S1359571Zheludev, N. I. & Kivshar, Y. S. From metamaterials to metadevices. Nature materials 11, 917–924 (2012).Ding, Y., Liu, Z., Qiu, C. & Shi, J. Metamaterial with simultaneously negative bulk modulus and mass density. Physical review letters 99, 093904 (2007).Christensen, J., Kadic, M., Kraft, O. & Wegener, M. Vibrant times for mechanical metamaterials. Mrs Communications 5, 453–462 (2015).Yang, Z., Mei, J., Yang, M., Chan, N. & Sheng, P. Membrane-type acoustic metamaterial with negative dynamic mass. Phys. Rev. Lett. 101, 204301 (2008).Cummer, S. A., Christensen, J. & Alù, A. Controlling sound with acoustic metamaterials. Nature Reviews Materials 1, 16001 (2016).Landy, N. I., Sajuyigbe, S., Mock, J., Smith, D. & Padilla, W. Perfect metamaterial absorber. Physical review letters 100, 207402 (2008).Watts, C. M., Liu, X. & Padilla, W. J. Metamaterial electromagnetic wave absorbers. Advanced materials 24 (2012).Cui, Y. et al. Plasmonic and metamaterial structures as electromagnetic absorbers. Laser & Photonics Reviews 8, 495–520 (2014).Lee, Y. P., Rhee, J. Y., Yoo, Y. J. & Kim, K. W. Metamaterials for perfect absorption. Springer series in materials science (ISSN 0933-033X 236 (2016).Cui, Y. et al. Ultrabroadband light absorption by a sawtooth anisotropic metamaterial slab. Nano letters 12, 1443–1447 (2012).Ding, F., Cui, Y., Ge, X., Jin, Y. & He, S. Ultra-broadband microwave metamaterial absorber. Applied physics letters 100, 103506 (2012).Mei, J. et al. Dark acoustic metamaterials as super absorbers for low-frequency sound. Nat. Commun. 3, 756 (2012).Ma, G., Yang, M., Xiao, S., Yang, Z. & Sheng, P. Acoustic metasurface with hybrid resonances. Nat. Mater. 13, 873–878 (2014).Romero-García, V. et al. Perfect and broadband acoustic absorption by critically coupled sub-wavelength resonators. Sci. Rep. 6, 19519 (2016).Jiang, X. et al. Ultra-broadband absorption by acoustic metamaterials. Applied Physics Letters 105, 243505 (2014).Leclaire, P., Umnova, O., Dupont, T. & Panneton, R. Acoustical properties of air-saturated porous material with periodically distributed dead-end poresa). J. Acoust. Soc. Am. 137, 1772–1782 (2015).Groby, J.-P., Huang, W., Lardeau, A. & Aurégan, Y. The use of slow waves to design simple sound absorbing materials. J. Appl. Phys. 117, 124903 (2015).Groby, J.-P., Pommier, R. & Aurégan, Y. Use of slow sound to design perfect and broadband passive sound absorbing materials. J. Acoust. Soc. Am. 139, 1660–1671 (2016).Li, Y. & Assouar, B. M. Acoustic metasurface-based perfect absorber with deep subwavelength thickness. Appl. Phys. Lett. 108, 063502 (2016).Romero-García, V., Theocharis, G., Richoux, O. & Pagneux, V. Use of complex frequency plane to design broadband and sub-wavelength absorbers. The Journal of the Acoustical Society of America 139, 3395–3403 (2016).Jiménez, N., Huang, W., Romero-García, V., Pagneux, V. & Groby, J.-P. Ultra-thin metamaterial for perfect and quasi-omnidirectional sound absorption. Applied Physics Letters 109, 121902 (2016).Jiménez, N., Romero-García, V., Pagneux, V. & Groby, J.-P. Quasiperfect absorption by subwavelength acoustic panels in transmission using accumulation of resonances due to slow sound. Phys. Rev. B 95, 014205 (2017).Achilleos, V., Theocharis, G., Richoux, O. & Pagneux, V. Non-hermitian acoustic metamaterials: Role of exceptional points in sound absorption. Physical Review B 95, 144303 (2017).Santillán, A. & Bozhevolnyi, S. I. Acoustic transparency and slow sound using detuned acoustic resonators. Phys. Rev. B 84, 064304 (2011).Chong, Y., Ge, L., Cao, H. & Stone, A. D. Coherent perfect absorbers: time-reversed lasers. Physical review letters 105, 053901 (2010).Wan, W. et al. Time-reversed lasing and interferometric control of absorption. Science 331, 889–892 (2011).Groby, J.-P., Duclos, A., Dazel, O., Boeckx, L. & Lauriks, W. Absorption of a rigid frame porous layer with periodic circular inclusions backed by a periodic grating. J. Acoust. Soc. Am. 129, 3035–3046 (2011).Lagarrigue, C., Groby, J., Tournat, V., Dazel, O. & Umnova, O. Absorption of sound by porous layers with embedded periodic arrays of resonant inclusions. J. Acoust. Soc. Am. 134, 4670–4680 (2013).Boutin, C. Acoustics of porous media with inner resonators. J. Acoust. Soc. Am. 134, 4717–4729 (2013).Groby, J.-P. et al. Enhancing the absorption properties of acoustic porous plates by periodically embedding helmholtz resonators. J. Acoust. Soc. Am. 137, 273–280 (2015).Wu, T., Cox, T. & Lam, Y. From a profiled diffuser to an optimized absorber. The Journal of the Acoustical Society of America 108, 643–650 (2000).Yang, M., Chen, S., Fu, C. & Sheng, P. Optimal sound-absorbing structures. Materials Horizons (2017).Yang, J., Lee, J. S. & Kim, Y. Y. Multiple slow waves in metaporous layers for broadband sound absorption. Journal of Physics D: Applied Physics 50, 015301 (2016).Merkel, A., Theocharis, G., Richoux, O., Romero-García, V. & Pagneux, V. Control of acoustic absorption in one-dimensional scattering by resonant scatterers. Appl. Phys. Lett. 107, 244102 (2015).Piper, J. R., Liu, V. & Fan, S. Total absorption by degenerate critical coupling. Appl. Phys. Lett. 104, 251110 (2014).Yang, M. et al. Subwavelength total acoustic absorption with degenerate resonators. Appl. Phys. Lett. 107, 104104 (2015).Jiménez, N. et al. Broadband quasi perfect absorption using chirped multi-layer porous materials. AIP Advances 6, 121605 (2016).Tsakmakidis, K. L., Boardman, A. D. & Hess, O. Trapped rainbow storage of light in metamaterials. Nature 450, 397–401 (2007).Zhu, J. et al. Acoustic rainbow trapping. Scientific reports 3 (2013).Romero-Garcia, V., Picó, R., Cebrecos, A., Sanchez-Morcillo, V. & Staliunas, K. Enhancement of sound in chirped sonic crystals. Applied Physics Letters 102, 091906 (2013).Ni, X. et al. Acoustic rainbow trapping by coiling up space. Scientific reports 4 (2014).Colombi, A., Colquitt, D., Roux, P., Guenneau, S. & Craster, R. V. A seismic metamaterial: The resonant metawedge. Scientific reports 6 (2016).Powell, M. J. A fast algorithm for nonlinearly constrained optimization calculations. In Numerical analysis, 144–157 (Springer, 1978).Stinson, M. R. The propagation of plane sound waves in narrow and wide circular tubes, and generalization to uniform tubes of arbitrary cross-sectional shape. J. Acoust. Soc. Am. 89, 550–558 (1991).Theocharis, G., Richoux, O., García, V. R., Merkel, A. & Tournat, V. Limits of slow sound propagation and transparency in lossy, locally resonant periodic structures. New J. Phys. 16, 093017 (2014).Kergomard, J. & Garcia, A. Simple discontinuities in acoustic waveguides at low frequencies: critical analysis and formulae. J. Sound Vib. 114, 465–479 (1987).Dubos, V. et al. Theory of sound propagation in a duct with a branched tube using modal decomposition. Acta Acustica united with Acustica 85, 153–169 (1999).Mechel, F. P. Formulas of acoustics, 2nd ed. (Springer Science & Business Media, 2008)