Reducing GHG Emissions by Abandoning Agricultural Land use on Organic Soils - A Cost Assessment

Roughly 6.5% of the German utilized agricultural area is located on organic soils (fens and bogs). Nevertheless, the drainage of these areas in order to allow their agricultural utilization causes roughly a third of the greenhouse gas emissions (GHG) of the German agricultural sector, being equivalent to 4% of the total German GHG emissions. Obviously, German policies trying to reduce the GHG emissions successfully must tackle this issue. The abandonment of the cultivation of organic soils would be an effective policy to reduce the GHG emissions however the question remains whether it is an efficient measure compared with the other options? In the paper we assess the mitigation costs on the basis of the standard gross margin and tenure of the agriculturally used peatlands and with the results obtained from sector model RAUMIS. Without engineering and transaction costs the mitigation costs are in the magnitude of 10 to 45 € per to of CO2eq. This makes rewetting of peatlands at least in the medium and long run a fairly efficient options for reducing GHG emissions, especially as the implications on the sector due to reallocation affects are fairly small.GHG-Mitigation, Landuse, peatland, Environmental Economics and Policy, Land Economics/Use,

REDUCING GHG EMISSIONS BY ABANDONING AGRICULTURAL LAND USE ON ORGANIC SOILS

6.5% of the German UAA is located on organic soils (fens and bogs). Nevertheless, the drainage of these areas in order to allow their agricultural utilization causes roughly a third of the greenhouse gas emissions (GHG) of the German agricultural sector, being equivalent to 4% of the total German GHG emissions. Obviously, German policies trying to reduce the GHG emissions successfully must tackle this issue. The abandonment of the cultivation of organic soils would be an effective policy to reduce the GHG emissions however the question remains whether it is an efficient measure compared with the other options? In the paper we compare the land use on mineral and organic soils using the data of the farm structure survey. We assess the mitigation costs on the basis of the standard gross margin of the agriculturally used peatlands and with the sector model RAUMIS. Without engineering and transaction costs the mitigation costs are in the magnitude of 10 to 45 € per to of CO2eq.. This makes rewetting of peatlands at least in the medium and long run a fairly efficient options for reducing GHG emissions, especially as the implications on the sector are fairly small due to reallocation affects.Agricultural and Food Policy, Environmental Economics and Policy, Resource /Energy Economics and Policy,

Three-dimensional spontaneous magnetic reconnection in neutral current sheets

Magnetic reconnection in an antiparallel uniform Harris current sheet equilibrium, which is initially perturbed by a region of enhanced resistivity limited in all three dimensions, is investigated through compressible magnetohydrodynamic simulations. Variable resistivity, coupled to the dynamics of the plasma by an electron-ion drift velocity criterion, is used during the evolution. A phase of magnetic reconnection amplifying with time and leading to eruptive energy release is triggered only if the initial perturbation is strongly elongated in the direction of current flow or if the threshold for the onset of anomalous resistivity is significantly lower than in the corresponding two-dimensional case. A Petschek-like configuration is then built up for \sim 100 Alfven times, but remains localized in the third dimension. Subsequently, a change of topology to an O-line at the center of the system (``secondary tearing'') occurs. This leads to enhanced and time-variable reconnection, to a second pair of outflow jets directed along the O-line, and to expansion of the reconnection process into the third dimension. High parallel current density components are created mainly near the region of enhanced resistivity.Comment: 22 pages, 14 figures (Figs. 3,9,10, and 14 as external GIF-Files

Calculation of Mutual Information for Partially Coherent Gaussian Channels with Applications to Fiber Optics

The mutual information between a complex-valued channel input and its complex-valued output is decomposed into four parts based on polar coordinates: an amplitude term, a phase term, and two mixed terms. Numerical results for the additive white Gaussian noise (AWGN) channel with various inputs show that, at high signal-to-noise ratio (SNR), the amplitude and phase terms dominate the mixed terms. For the AWGN channel with a Gaussian input, analytical expressions are derived for high SNR. The decomposition method is applied to partially coherent channels and a property of such channels called "spectral loss" is developed. Spectral loss occurs in nonlinear fiber-optic channels and it may be one effect that needs to be taken into account to explain the behavior of the capacity of nonlinear fiber-optic channels presented in recent studies.Comment: 30 pages, 9 figures, accepted for publication in IEEE Transactions on Information Theor

Оценка амплитуд и вероятностей многоэлектронных переходов в атомах на основе многочастичной теории возмущений

Излагается подход к получению приближенных формул для оценки амплитуд и вероятностей многоэлектронных переходов в атомах. Приближенные формулы получены на основе точных, в рамках определенного порядка теории возмущений, выражений и физически обосновываются. Подход позволяет не только сравнительно просто оценивать вероятности переходов и сечения процессов, но и открывает возможность выявлять доминирующие физические механизмы переходов. Рассматриваются приближения встряски, резонанса в непрерывном спектре, резонанса в дискретном спектре, неортогональных орбиталей