Decadal increase in groundwater inorganic carbon concentrations across Sweden

Groundwater concentrations of dissolved inorganic carbon and carbon dioxide have increased by 28% and 49%, respectively, across Sweden between 1980 and 2020 due to partial recovery from historic anthropogenic acid deposition and increased soil respiration, suggest geochemical model calculations.Groundwater is one of the largest continental carbon reservoirs and tightly linked to globally important carbon fluxes such as uptake on land, degassing from inland waters and delivery to oceans. Despite emerging evidence that these fluxes are sensitive to environmental changes, long-term carbon dynamics in groundwater remain widely unknown. Here I show that dissolved inorganic carbon and carbon dioxide concentrations in groundwater, calculated from environmental monitoring data (e.g. alkalinity, pH), have increased on average by 28% and 49%, respectively, across Sweden during 1980-2020. I attribute the observed changes mainly to a partial recovery from atmospheric sulfate deposition and associated shifts in weathering pathways, but also to enhanced soil respiration. The results highlight previously neglected long-term and large-scale dynamics in groundwater carbon cycling. These dynamics should be included in carbon cycle models for accurate evaluations and predictions of the effects of environmental changes on landscape and global carbon stocks and fluxes

N-body Gravity and the Schroedinger Equation

We consider the problem of the motion of $N$ bodies in a self-gravitating system in two spacetime dimensions. We point out that this system can be mapped onto the quantum-mechanical problem of an N-body generalization of the problem of the H$_{2}^{+}$ molecular ion in one dimension. The canonical gravitational N-body formalism can be extended to include electromagnetic charges. We derive a general algorithm for solving this problem, and show how it reduces to known results for the 2-body and 3-body systems.Comment: 15 pages, Latex, references added, typos corrected, final version that appears in CQ

Anomalous electron trapping by localized magnetic fields

We consider an electron with an anomalous magnetic moment g>2 confined to a plane and interacting with a nonzero magnetic field B perpendicular to the plane. We show that if B has compact support and the magnetic flux in the natural units is F\ge 0, the corresponding Pauli Hamiltonian has at least 1+[F] bound states, without making any assumptions about the field profile. Furthermore, in the zero-flux case there is a pair of bound states with opposite spin orientations. Using a Birman-Schwinger technique, we extend the last claim to a weak rotationally symmetric field with B(r) = O(r^{-2-\delta}) correcting thus a recent result. Finally, we show that under mild regularity assumptions the existence can be proved for non-symmetric fields with tails as well.Comment: A LaTeX file, 12 pages; to appear in J. Phys. A: Math. Ge

Self-consistent solution for the polarized vacuum in a no-photon QED model

We study the Bogoliubov-Dirac-Fock model introduced by Chaix and Iracane ({\it J. Phys. B.}, 22, 3791--3814, 1989) which is a mean-field theory deduced from no-photon QED. The associated functional is bounded from below. In the presence of an external field, a minimizer, if it exists, is interpreted as the polarized vacuum and it solves a self-consistent equation. In a recent paper math-ph/0403005, we proved the convergence of the iterative fixed-point scheme naturally associated with this equation to a global minimizer of the BDF functional, under some restrictive conditions on the external potential, the ultraviolet cut-off $\Lambda$ and the bare fine structure constant $\alpha$. In the present work, we improve this result by showing the existence of the minimizer by a variational method, for any cut-off $\Lambda$ and without any constraint on the external field. We also study the behaviour of the minimizer as $\Lambda$ goes to infinity and show that the theory is "nullified" in that limit, as predicted first by Landau: the vacuum totally kills the external potential. Therefore the limit case of an infinite cut-off makes no sense both from a physical and mathematical point of view. Finally, we perform a charge and density renormalization scheme applying simultaneously to all orders of the fine structure constant $\alpha$, on a simplified model where the exchange term is neglected.Comment: Final version, to appear in J. Phys. A: Math. Ge

Unraveling the Contribution of Turbulence and Bubbles to Air-Water Gas Exchange in Running Waters

Quantifying air-water gas exchange is critical for estimating greenhouse gas fluxes and metabolism in aquatic ecosystems. In high-energy streams, the gas exchange rate k is poorly constrained, due to an incomplete understanding of turbulence and bubble contributions to k. We performed a flume experiment with air bubble additions to evaluate the combined effects of turbulence and bubbles on k for helium, argon, xenon, and methane. We created contrasting hydraulic conditions by varying channel slope, bed roughness, water discharge, and bubble flux. We found that k increased from 1-4 to 17-66 m d(-1) with increases in turbulence and bubble flux metrics. Mechanistic models that explicitly account for these metrics, as well as gas diffusivity and solubility, agreed well with the data and indicated that bubble-mediated gas exchange accounted for 64-93% of k. Bubble contributions increased with bubble flux but were independent of gas type, as bubbles did not equilibrate with the water. This was evident through modeled bubble life and equilibration times inferred from bubble size distributions obtained from underwater sound spectra. Sound spectral properties correlated well with turbulence and bubble flux metrics. Our results demonstrate that (a) mechanistic models can be applied to separate free surface- and bubble-mediated gas exchange in running waters, (b) bubble life and equilibration times are critical for accurate scaling of k between different gases, and (c) ambient sound spectra can be used to approximate contributions of turbulence and bubbles

Biotechnology for developing-country agriculture: problems and opportunities

Contents: Brief 1. Overview / Gabrielle J. Persley and John J. Doyle Brief 2. Biotechnology and food and nutrition needs / Richard Flavell Brief 3. Biotechnology and animal vaccines / W. Ivan Morrison Brief 4. The role of the private sector / Clive James and Anatole Krattiger Brief 5. Disentangling risk issues / Klaus M. Leisinger Brief 6. Safe use of biotechnology / Calestous Juma and Aarti Gupta Brief 7. Intellectual property protection / John H. Barton Brief 8. Research policy and management issues / Joel I. Cohen, Cesar Falconi, and John Komen Brief 9. Developing appropriate policies / Per Pinstrup-Andersen [IFPRI staff] Brief 10. Letter to a minister / Gabrielle J. Persley.Biotechnology Developing countries., Agricultural biotechnology Developing countries.,

Interaction induced delocalization of two particles: large system size calculations and dependence on interaction strength

The localization length $L_2$ of two interacting particles in a one-dimensional disordered system is studied for very large system sizes by two efficient and accurate variants of the Green function method. The numerical results (at the band center) can be well described by the functional form $L_2=L_1[0.5+c(U) L_1]$ where $L_1$ is the one-particle localization length and the coefficient $c(U)\approx 0.074 |U|/(1+|U|)$ depends on the strength $U$ of the on-site Hubbard interaction. The Breit-Wigner width or equivalently the (inverse) life time of non-interacting pair states is analytically calculated for small disorder and taking into account the energy dependence of the one-particle localization length. This provides a consistent theoretical explanation of the numerically found $U$-dependence of $c(U)$.Comment: 8 pages, 5 figures, LaTeX, EPJ macro package, submitted to the European Physical Journal

Localization and absence of Breit-Wigner form for Cauchy random band matrices

We analytically calculate the local density of states for Cauchy random band matrices with strongly fluctuating diagonal elements. The Breit-Wigner form for ordinary band matrices is replaced by a Levy distribution of index $\mu=1/2$ and the characteristic energy scale $\alpha$ is strongly enhanced as compared to the Breit-Wigner width. The unperturbed eigenstates decay according to the non-exponential law $\propto e^{-\sqrt{\alpha t}}$. We analytically determine the localization length by a new method to derive the supersymmetric non-linear $\sigma$ model for this type of band matrices.Comment: 4 pages, 1 figur

Eigenfunction structure and scaling of two interacting particles in the one-dimensional Anderson model

The localization properties of eigenfunctions for two interacting particles in the one-dimensional Anderson model are studied for system sizes up to $N=5000$ sites corresponding to a Hilbert space of dimension $\approx 10^7$ using the Green function Arnoldi method. The eigenfunction structure is illustrated in position, momentum and energy representation, the latter corresponding to an expansion in non-interacting product eigenfunctions. Different types of localization lengths are computed for parameter ranges in system size, disorder and interaction strengths inaccessible until now. We confirm that one-parameter scaling theory can be successfully applied provided that the condition of $N$ being significantly larger than the one-particle localization length $L_1$ is verified. The enhancement effect of the two-particle localization length $L_2$ behaving as $L_2\sim L_1^2$ is clearly confirmed for a certain quite large interval of optimal interactions strengths. Further new results for the interaction dependence in a very large interval, an energy value outside the band center, and different interaction ranges are obtained.Comment: 26 pages, 19 png and pdf figures, high quality gif files for panels of figures 1-4 are available at http://www.quantware.ups-tlse.fr/QWLIB/tipdisorder1d, final published version with minor corrections/revisions, addition of Journal reference and DO

Standards, Innovation Incentives, and the Formation of Patent Pools

Technological standards give rise to a complements problem that affects pricing and innovation incentives of technology producers. In this paper I discuss how patent pools can be used to solve these problems and what incentives patent holders have to form a patent pool. I offer some suggestions how competition authorities can foster the formation of welfare increasing patent pools