Controlling electron-electron correlation in frustrated double ionization of molecules with orthogonally polarized two-color laser fields

We demonstrate the control of electron-electron correlation in frustrated double ionization (FDI) of the two-electron triatomic molecule D$_{3}^{+}$ when driven by two orthogonally polarized two-color laser fields. We employ a three-dimensional semi-classical model that fully accounts for the electron and nuclear motion in strong fields. We analyze the FDI probability and the distribution of the momentum of the escaping electron along the polarization direction of the longer wavelength and more intense laser field. These observables when considered in conjunction bear clear signatures of the prevalence or absence of electron-electron correlation in FDI, depending on the time-delay between the two laser pulses. We find that D$_{3}^{+}$ is a better candidate compared to H$_{2}$ for demonstrating also experimentally that electron-electron correlation indeed underlies FDI.Comment: 5 pages, 4 figure

The uniqueness of the invariant polarisation-tensor field for spin-1 particles in storage rings

We argue that the invariant tensor field introduced in [1] is unique under the condition that the invariant spin field is unique, and thereby complete that part of the discussion in that paper.Comment: 8 page

Combined grazing incidence RBS and TEM analysis of luminescent nano-SiGe/SiO2 multilayers.

Multilayer structures with five periods of amorphous SiGe nanoparticles/SiO2 layers with different thickness were deposited by Low Pressure Chemical Vapor Deposition and annealed to crystallize the SiGe nanoparticles. The use of grazing incidence RBS was necessary to obtain sufficient depth resolution to separate the signals arising from the individual layers only a few nm thick. The average size and areal density of the embedded SiGe nanoparticles as well as the oxide interlayer thickness were determined from the RBS spectra. Details of eventual composition changes and diffusion processes caused by the annealing processes were also studied. Transmission Electron Microscopy was used to obtain complementary information on the structural parameters of the samples in order to check the information yielded by RBS. The study revealed that annealing at 900 °C for 60 s, enough to crystallize the SiGe nanoparticles, leaves the structure unaltered if the interlayer thickness is around 15 nm or higher

Empirical Assessment of Baseline Conservation Tillage Adoption Rates and Soil Carbon Sequestration in the Upper Mississippi River Basin

The study proposes a methodology for developing a carbon sequestration baseline attributable to the current use of conservation tillage. An integral component of the methodology is the explicit acknowledgment that there is an uncertainty in the baseline because of the uncertainty associated with the use of econometrically estimated models. The results of applying the method to a major crop production area, the Upper Mississippi River Basin in the central United States, are reported for two major crops in the region, corn and soybeans. The approach to estimation of the baseline should be readily transferable to other geographic areas and conservation practices.Environmental Economics and Policy,

Multiple Benefits of Carbon-Friendly Agricultural Practices: Empirical Assessment of Conservation Tillage in Iowa

In this study, we estimate empirically the multiple benefits of a subsidy policy that would offer payments to farmers in return for the adoption of conservation tillage and compare the outcomes of alternative targeting designs for such a policy. Using data for roughly 12,000 National Resource Inventory (NRI) points, we simulate for the state of Iowa the least-cost policy schemes for offering payment incentives. We use an economic model of conservation tillage adoption to evaluate the costs of adoption, and we use a model that simulates physical processes (Environmental Policy Integrated Climate, or EPIC) to estimate the environmental benefits of adoption at each of the NRI points. We assess the costs and environmental consequences of two targeting options. The first is a practice-based policy instrument that maximizes the acres of land in conservation tillage, regardless of the level of environmental benefits achieved. The second is a performance-based instrument that yields the highest amount of environmental benefits per dollar spent. We consider four performance-based benefits: carbon sequestration in agricultural soils, reduction in nitrogen runoff, reduction of erosion of soil by wind, and reduction of erosion of soil by water. We find that the practice-based instrument provides high proportions of the four benefits relative to the performance-based instrument, especially at higher budget levels. Similarly, we estimate that targeting one of the four benefits provides high percentages of the other benefits compared to the amounts obtainable if they were targeted directly.conservation tillage, multiple benefits, subsidy policy, targeting.

Institutions and the Value of Nonpoint Source Measurement Technology: Carbon Sequestration in Agricultural Soils

The development of technologies for accurate field-scale carbon assessment allows the implementation of more efficient policies than can be implemented in their absence. We estimate the value of accurate measurement technology by estimating the gains from implementing a more efficient policy, one that targets carbon reductions at the field scale but requires accurate field-scale measurement technology, relative to a practice-based policy that can be implemented in the absence of such technology. We find large cost savings due to improved targeting of conservation tillage subsidies for the state of Iowa. The cost savings depend significantly on the choice of baseline carbon, while the ability of the government to cost discriminate has little impact on the value of accurate measurement technology.carbon sequestration, green payment policy, value of measurement technology.

Kuhn-Tucker Estimation of Recreation Demand – A Study of Temporal Stability

The paper examines the Kuhn Tucker model in the context of estimating recreation demand when the choice set it very large. It examines the temporal stability of parameter estimates using multiple years of data on trips to 127 lakes in Iowa made by households in Iowa. The study finds that for the given dataset, the estimates derived from a Kuhn-Tucker model are largely stable over time.Recreation demand, Kuhn-Tucker, Temporal Stability, Environmental Economics and Policy, C2, Q2,

Slingshot non-sequential double ionization as a gate to anti-correlated two electron escape

At intensities below-the-recollision threshold, we show that re-collision-induced excitation with one electron escaping fast after re-collision and the other electron escaping with a time delay via a Coulomb slingshot motion is one of the most important mechanisms of non-sequential double ionization, for strongly-driven He at 400 nm. Slingshot-NSDI is a general mechanism present for a wide range of low intensities and pulse durations. Anti-correlated two-electron escape is its striking hallmark. This mechanism offers an alternative explanation of anti-correlated two-electron escape obtained in previous studies.Comment: 6 pages, 3 figure

THE SUBSIDY FOR ADOPTING CONSERVATION TILLAGE: ESTIMATION FROM OBSERVED BEHAVIOR

Due to payoff uncertainties combined with risk aversion and/or real options, farmers may demand a premium in order to adopt conservation tillage practices, over and above the compensation for the expected profit losses (if any). We propose a method of directly estimating the financial incentives for adopting conservation tillage and distinguishing between the expected payoff and the premium of adoption based on observed behavior. We find that the premium may play a significant role in farmers' adoption decisions. Even for non-adopters, conservation tillage provides a higher payoff than does conventional tillage on average, as agronomists have argued. However, non-adopters do not use conservation tillage because the expected profit gain alone does not fully compensate them for the uncertainties. To induce additional adoption, subsidies could be used. We find that in Iowa on average, the mean subsidy needed is $2.40 per acre per year for corn and$3.50 per acre per year for soybeans.Land Economics/Use,