95 research outputs found
Productivity of silvoarable systems established with Prunus avium L. in Galicia (NW Spain)
info:eu-repo/semantics/publishedVersio
JIMWLK evolution in the Gaussian approximation
We demonstrate that the Balitsky-JIMWLK equations describing the high-energy
evolution of the n-point functions of the Wilson lines (the QCD scattering
amplitudes in the eikonal approximation) admit a controlled mean field
approximation of the Gaussian type, for any value of the number of colors Nc.
This approximation is strictly correct in the weak scattering regime at
relatively large transverse momenta, where it reproduces the BFKL dynamics, and
in the strong scattering regime deeply at saturation, where it properly
describes the evolution of the scattering amplitudes towards the respective
black disk limits. The approximation scheme is fully specified by giving the
2-point function (the S-matrix for a color dipole), which in turn can be
related to the solution to the Balitsky-Kovchegov equation, including at finite
Nc. Any higher n-point function with n greater than or equal to 4 can be
computed in terms of the dipole S-matrix by solving a closed system of
evolution equations (a simplified version of the respective Balitsky-JIMWLK
equations) which are local in the transverse coordinates. For simple
configurations of the projectile in the transverse plane, our new results for
the 4-point and the 6-point functions coincide with the high-energy
extrapolations of the respective results in the McLerran-Venugopalan model. One
cornerstone of our construction is a symmetry property of the JIMWLK evolution,
that we notice here for the first time: the fact that, with increasing energy,
a hadron is expanding its longitudinal support symmetrically around the
light-cone. This corresponds to invariance under time reversal for the
scattering amplitudes.Comment: v2: 45 pages, 4 figures, various corrections, section 4.4 updated, to
appear in JHE
Modelled agroforestry outputs at field and farm scale to support biophysical and environmental assessments
This report, comprising Deliverable 6.17, in the AGFORWARD project brings together examples of modelled outputs at field and farm scale to support the biophysical, social, and environmental assessment of the innovations selected from work-packages 2 to 5.N/
Agroforestry is paying off – Economic evaluation of ecosystem services in European landscapes with and without agroforestry systems
The study assessed the economic performance of marketable ecosystem services (ES) (biomass production) and non-marketable ecosystem services and dis-services (groundwater, nutrient loss, soil loss, carbon sequestration, pollination deficit) in 11 contrasting European landscapes dominated by agroforestry land use compared to business as usual agricultural practice. The productivity and profitability of the farming activities and the associated ES were quantified using environmental modelling and economic valuation. After accounting for labour and machinery costs the financial value of the outputs of Mediterranean agroforestry systems tended to be greater than the corresponding agricultural system; but in Atlantic and Continental regions the agricultural system tended to be more profitable. However, when economic values for the associated ES were included, the relative profitability of agroforestry increased. Agroforestry landscapes: (i) were associated to reduced externalities of pollution from nutrient and soil losses, and (ii) generated additional benefits from carbon capture and storage and thus generated an overall higher economic gain. Our findings underline how a market system that includes the values of broader ES would result in land use change favouring multifunctional agroforestry. Imposing penalties for dis-services or payments for services would reflect their real world prices and would make agroforestry a more financially profitable system
Effective Rheology of Bubbles Moving in a Capillary Tube
We calculate the average volumetric flux versus pressure drop of bubbles
moving in a single capillary tube with varying diameter, finding a square-root
relation from mapping the flow equations onto that of a driven overdamped
pendulum. The calculation is based on a derivation of the equation of motion of
a bubble train from considering the capillary forces and the entropy production
associated with the viscous flow. We also calculate the configurational
probability of the positions of the bubbles.Comment: 4 pages, 1 figur
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