13,430 research outputs found

    MODELING TIMBER SUPPLY, FUEL-WOOD, AND ATMOSPHERIC CARBON MITIGATION

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    There is general agreement that global warming is occurring and that the main contributor to this probably is the buildup of green house gases, GHG, in the atmosphere. Two main contributors are the utilization of fossil fuels and the deforestation of many regions of the world. This paper examines a number of current issues related to mitigating the global warming problem through forestry. We use discrete time optimal control to model a simplified carbon cycle. The burning of fossil fuels increases atmospheric carbon while the burning of fuel-wood along with its forest source maintain an atmospheric carbon level. The standing timber in the forests is a carbon sink, as are wood buildings and structures, and fossil fuel in the ground. Through time the buildings and structures decay and release carbon to the atmosphere. We also present a numerical example to help illustrate the characteristics of the model. The conclusions are that the forest sector can have a significant impact.Environmental Economics and Policy,

    VALUING WILDLIFE MANAGEMENT: A UTAH DEER HERD

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    Managers of public wildlife resources generally are concerned with enhancing the quality of recreation by increasing wildlife through habitat manipulation. However, current recreation valuation studies have focused upon variables that are inappropriate for use in these management decisions. The economic criterion for these decisions should be the value of a change in the stock of the wildlife population compared to its cost. An estimate of such a value was made for the Oak Creek deer herd in Utah, using a household production function approach in an optimal control framework. The value of an additional deer in the herd was estimated to be approximately $40.00.Resource /Energy Economics and Policy,

    Anisotropic Stark Effect and Electric-Field Noise Suppression for Phosphorus Donor Qubits in Silicon

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    We report the use of novel, capacitively terminated coplanar waveguide (CPW) resonators to measure the quadratic Stark shift of phosphorus donor qubits in Si. We confirm that valley repopulation leads to an anisotropic spin-orbit Stark shift depending on electric and magnetic field orientations relative to the Si crystal. By measuring the linear Stark effect, we estimate the effective electric field due to strain in our samples. We show that in the presence of this strain, electric-field sources of decoherence can be non-negligible. Using our measured values for the Stark shift, we predict magnetic fields for which the spin-orbit Stark effect cancels the hyperfine Stark effect, suppressing decoherence from electric-field noise. We discuss the limitations of these noise-suppression points due to random distributions of strain and propose a method for overcoming them
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