A standardised method for measuring in situ denitrification in shallow aquifers: numerical validation and measurements in riparian wetlands

A tracer test to examine in situ denitrification in shallow groundwater by a piezometer with a packer system used bromide as a tracer of dilution and acetylene (10%) to block the denitrification process at the nitrous oxide stage. During the test, dissolved oxygen, nitrate (NO3-), bromide (Br-), nitrous oxide (N2O) and dissolved organic carbon (DOC) were measured. To calibrate the experimental method, comparison with numerical simulations of the groundwater transfer were carried out, taking into account the environmental characteristics. The method was tested by measurements undertaken in different environmental conditions (geology, land use and hydrology) in two riparian wetlands. Denitrification rates measured by this method ranged from 5.7 10-6 g N-NO3-L-1 h-1 to 1.97 10-3 g N-NO3-L-1 h-1 The method is applicable in shallow aquifers with a permeability from 10-2 to 10-4m s-1

A non-linear degenerate equation for direct aggregation and traveling wave dynamics

The gregarious behavior of individuals of populations is an important factor in avoiding predators or for reproduction. Here, by using a random biased walk approach, we build a model which, after a transformation, takes the general form [u_{t}=[D(u)u_{x}]_{x}+g(u)] . The model involves a density-dependent non-linear diffusion coefficient [D] whose sign changes as the population density [u] increases. For negative values of [D] aggregation occurs, while dispersion occurs for positive values of [D] . We deal with a family of degenerate negative diffusion equations with logistic-like growth rate [g] . We study the one-dimensional traveling wave dynamics for these equations and illustrate our results with a couple of examples. A discussion of the ill-posedness of the partial differential equation problem is included

Nitrogen dynamics in the shallow groundwater of a riparian wetland zone of the Garonne, SW France: nitrate inputs, bacterial densities, organic matter supply and denitrification measurements

This study highlights the role of interactions between surface and sub-surface water of the riparian zone of a large river (the Garonne, SW France). Information is given about the role of surface water in supplying Dissolved Organic Carbon (DOC ) to the riparian zone for nitrate removal processes. The densities of bacteria (up to 3.3106 cell m L-1) in groundwater are strongly conditioned by the water moving during flood events. Total bacterial densities in groundwater were related to surface water bacterial densities. In sediment, total bacteria are attached mainly to fine particles (90 % in the fraction < 1 mm). Spatial variations in organic carbon and nitrate content in groundwater at the site studied are correlated with exchanges between the groundwater and the river, from the upstream to the downstream part of the meander. Total bacterial densities, nitrate and decressing organic carbon concentrations follow the same pattern. These results suggest that, in this kind of riparian wetland, nitrate from alluvial groundwater influenced by agricultural practices may be denitrified by bacteria in the presence of organic carbon from river surface water

Topological Dual Systems for Spaces of Vector Measure p-Integrable Functions

[EN] We show a Dvoretzky-Rogers type theorem for the adapted version of the q-summing operators to the topology of the convergence of the vector valued integrals on Banach function spaces. In the pursuit of this objective we prove that the mere summability of the identity map does not guarantee that the space has to be finite dimensional, contrary to the classical case. Some local compactness assumptions on the unit balls are required. Our results open the door to new convergence theorems and tools regarding summability of series of integrable functions and approximation in function spaces, since we may find infinite dimensional spaces in which convergence of the integrals, our vector valued version of convergence in the weak topology, is equivalent to the convergence with respect to the norm. Examples and applications are also given.This work was supported by the Ministerio de Economia y Competitividad (Spain) under Grants MTM2015-66823-C2-2-P (P. Rueda) and MTM2012-36740-C02-02 (E. A. Sanchez Perez).Rueda, P.; Sánchez Pérez, EA. (2016). Topological Dual Systems for Spaces of Vector Measure p-Integrable Functions. Journal of Function Spaces. 1-8. https://doi.org/10.1155/2016/3763649S18Pérez, E. A. S. (2004). Vector measure duality and tensor product representations of $L_p$-spaces of vector measures. Proceedings of the American Mathematical Society, 132(11), 3319-3326. doi:10.1090/s0002-9939-04-07521-5Lewis, D. (1970). Integration with respect to vector measures. Pacific Journal of Mathematics, 33(1), 157-165. doi:10.2140/pjm.1970.33.157Lewis, D. R. (1972). On integrability and summability in vector spaces. Illinois Journal of Mathematics, 16(2), 294-307. doi:10.1215/ijm/1256052286Curbera, G. P. (1995). Banach Space Properties of L 1 of a Vector Measure. Proceedings of the American Mathematical Society, 123(12), 3797. doi:10.2307/2161909Ferrando, I. (2011). Factorization theorem for 1-summing operators. Czechoslovak Mathematical Journal, 61(3), 785-793. doi:10.1007/s10587-011-0027-9Fernández, A., Mayoral, F., Naranjo, F., Sáez, C., & Sánchez-Pérez, E. A. (2006). Spaces of p-integrable Functions with Respect to a Vector Measure. Positivity, 10(1), 1-16. doi:10.1007/s11117-005-0016-zOkada, S., & Ricker, W. J. (1995). The range of the integration map of a vector measure. Archiv der Mathematik, 64(6), 512-522. doi:10.1007/bf01195133Okada, S., Ricker, W. J., & Rodríguez-Piazza, L. (2002). Compactness of the integration operator associated with a vector measure. Studia Mathematica, 150(2), 133-149. doi:10.4064/sm150-2-3Okada, S., Ricker, W. J., & Rodríguez-Piazza, L. (2011). Operator ideal properties of vector measures with finite variation. Studia Mathematica, 205(3), 215-249. doi:10.4064/sm205-3-2FERRANDO, I., & SÁNCHEZ PÉREZ, E. A. (2009). TENSOR PRODUCT REPRESENTATION OF THE (PRE)DUAL OF THE Lp-SPACE OF A VECTOR MEASURE. Journal of the Australian Mathematical Society, 87(2), 211-225. doi:10.1017/s1446788709000196Ferrando, I., & Rodríguez, J. (2008). The weak topology on Lp of a vector measure. Topology and its Applications, 155(13), 1439-1444. doi:10.1016/j.topol.2007.12.014Galaz-Fontes, F. (2010). The dual space of L p of a vector measure. Positivity, 14(4), 715-729. doi:10.1007/s11117-010-0071-yRueda, P., & Sánchez-Pérez, E. A. (2015). Compactness in spaces of p-integrable functions with respect to a vector measure. Topological Methods in Nonlinear Analysis, 45(2), 641. doi:10.12775/tmna.2015.030Rueda, P., & Sánchez-Pérez, E. A. (2014). Factorization Theorems for Homogeneous Maps on Banach Function Spaces and Approximation of Compact Operators. Mediterranean Journal of Mathematics, 12(1), 89-115. doi:10.1007/s00009-014-0384-3S�nchez P�rez, E. A. (2003). Vector measure orthonormal functions and best approximation for the 4-norm. Archiv der Mathematik, 80(2), 177-190. doi:10.1007/s00013-003-0450-8Okada, S., Ricker, W. J., & Pérez, E. A. S. (2014). Lattice copies of c0and l∞in spaces of integrable functions for a vector measure. Dissertationes Mathematicae, 500, 1-68. doi:10.4064/dm500-0-

Evidence of ongoing radial migration in NGC 6754: Azimuthal variations of the gas properties

Understanding the nature of spiral structure in disk galaxies is one of the main, and still unsolved questions in galactic astronomy. However, theoretical works are proposing new testable predictions whose detection is becoming feasible with recent development in instrumentation. In particular, streaming motions along spiral arms are expected to induce azimuthal variations in the chemical composition of a galaxy at a given galactic radius. In this letter we analyse the gas content in NGC 6754 with VLT/MUSE data to characterise its 2D chemical composition and H$\alpha$ line-of-sight velocity distribution. We find that the trailing (leading) edge of the NGC 6754 spiral arms show signatures of tangentially-slower, radially-outward (tangentially-faster, radially-inward) streaming motions of metal-rich (poor) gas over a large range of radii. These results show direct evidence of gas radial migration for the first time. We compare our results with the gas behaviour in a $N$-body disk simulation showing spiral morphological features rotating with a similar speed as the gas at every radius, in good agreement with the observed trend. This indicates that the spiral arm features in NGC 6754 may be transient and rotate similarly as the gas does at a large range of radii.Comment: 8 pages, 4 figures, accepted for publication in ApJL 2016 September 2

UV Dichroism in Vertically Aligned Nematic Displays

Vertically aligned negative nematics are employed in high-end projection applications, where extremely high light fluxes are employed. Under these conditions, the UV photochemical stability of the material becomes an issue that must be included in the characterization process of such devices. Photochemical aging tests for vertically aligned microdisplay, however, must take into account the linear dichroism shown by the liquid crystal material upon switching. In this work a method to evaluate UV linear dichroism is described. The method is included in a comparative study of the electrooptical performance of two negative nematic mixtures, one experimental and one commercial

The role of stellar radial motions in shaping galaxy surface brightness profiles

Aims. The physics driving features such as breaks observed in galaxy surface brightness (SB) profiles remains contentious. Here, we assess the importance of stellar radial motions in shaping their characteristics. Methods. We use the simulated Milky Way-mass cosmological discs from the Ramses Disc Environment Study (RaDES) to characterise the radial redistribution of stars in galaxies displaying type-I (pure exponentials), II (downbending), and III (upbending) SB profiles. We compare radial profiles of the mass fractions and the velocity dispersions of different sub-populations of stars according to their birth and current location. Results. Radial redistribution of stars is important in all galaxies regardless of their light profiles. Type-II breaks seem to be a consequence of the combined effects of outward-moving and accreted stars. The former produce shallower inner profiles (lack of stars in the inner disc) and accumulate material around the break radius and beyond, strengthening the break; the latter can weaken or even convert the break into a pure exponential. Further accretion from satellites can concentrate material in the outermost parts, leading to type-III breaks that can coexist with type-II breaks, but situated further out. Type-III galaxies would be the result of an important radial redistribution of material throughout the entire disc, as well as a concentration of accreted material in the outskirts. In addition, type-III galaxies display the most efficient radial redistribution and the largest number of accreted stars, followed by type-I and II systems, suggesting that type-I galaxies may be an intermediate case between types-II and III. In general, the velocity dispersion profiles of all galaxies tend to flatten or even increase around the locations where the breaks are found. The age and metallicity profiles are also affected, exhibiting different inner gradients depending on their SB profile, being steeper in the case of type-II systems (as found observationally). The steep type-II profiles might be inherent to their formation rather than acquired via radial redistribution