Optimal Economic Landscapes with Habitat Fragmentation Effects

Habitat fragmentation is widely considered a primary threat to biodiversity. This paper develops a theoretical model of land use to analyze the optimal conservation of landscapes when land quality is spatially heterogeneous and wildlife habitat is fragmented and socially valuable. When agriculture is the primary cause of fragmentation, we show that reforestation efforts should be targeted to the most fragmented landscapes with an aggregate share of forest equal to a threshold, defined by the ratio of the opportunity cost of conversion to the social value of core forest. When urban development is the primary cause of fragmentation, we show how spatial heterogeneity in amenities and household neighbor preferences affect the optimal landscape and the design of land-use policies.Land Economics/Use,

Targeting Incentives to Reduce Habitat Fragmentation

This paper develops a theoretical model to analyze the spatial targeting of incentives for the restoration of forested landscapes when wildlife habitat can be enhanced by reducing fragmentation. The key theoretical result is that the marginal net benefits of increasing forest are convex, indicating that corner solutions--converting either none or all of the agricultural land in a section to forest--may be optimal. Corner solutions are directly linked to the spatial process determining habitat benefits and the regulator's incomplete information regarding landowner opportunity costs. We present findings from a large-scale empirical landscape simulation that supports our key theoretical results.

URBAN SPRAWL AND OBESITY

In the U.S., urban sprawl and the rise in obesity rates have been two powerful trends during the latter half of the 20th century. Previous empirical work has found that obesity rates are influenced by labor market outcomes that are fundamentally shaped by the spatial pattern of developed land. We examine these potential linkages in an urban spatial model augmented to include time allocation and weight. Residents maximize utility defined over housing, weight, and food subject to a fixed time budget allocated to commuting, calorie expenditure, and work. We examine how weight is affected by commuting distance, food prices, and the rate of calorie expenditure; how a reduction in transportation costs affects weight throughout the city; and how initial weight affects location decisions. We identify, and explore the significance of, the conditions under which weight gain is associated with common features of sprawl.Food Consumption/Nutrition/Food Safety,

AMENITIES IN AN URBAN EQUILIBRIUM MODEL: RESIDENTIAL DEVELOPMENT IN PORTLAND, OREGON

This paper analyzes the effect of open space and other amenities on housing prices and development density within the framework of an urban equilibrium model. The model is estimated as a system of equations that includes households' residential choice decisions and developers' development decisions and emphasizes the importance of amenities in the formation of development patterns and property values. The model is applied to Portland, Oregon, where ambitious open space programs have been implemented. The results suggest that amenities are important: households are willing to pay more for newer houses located in areas of less dense development, with more open space, better views, less traffic congestion, and near amenity locations. For the developer, increases in housing prices result in an attempt to provide more and larger houses. The attempt to provide more houses, however, results in higher density, which will ultimately reduce prices. A simulation analysis evaluates the policy implications of the model results and indicates substantial benefits from alterations in housing patternsCommunity/Rural/Urban Development, R11, R21, R31,

A DYNAMIC ANALYSIS OF THE IMPACT OF WATER QUALITY POLICIES ON IRRIGATION INVESTMENT AND CROP CHOICE DECISIONS

A dynamic model is developed to analyze farmers' irrigation investment and crop choice decisions under alternative water quality protection policies. The model is applied to an empirical example in the Oklahoma High Plains. The choices of crops and irrigation systems and the resulting levels of irrigation, income, and nitrogen runoff and percolation are simulated over a ten-year period. An effluent tax on nitrogen runoff and percolation is shown to be effective in reducing nitrate pollution. The efficacy of cost sharing in adopting modern irrigation technologies and restrictions on irrigation water use depends on soil type. A tax on nitrogen use is shown to be the least effective policy.Crop selection, Dynamic optimization, Irrigation investment, Water quality, Crop Production/Industries,

R-parity violating effects in top quark FCNC productions at LHC

In the minimal supersymmetric model the R-parity violating top quark interactions, which are so far weakly constrained, can induce various flavor-changing neutral-current (FCNC) productions for the top quark at the Large Hadron Collider (LHC). In this work we assume the presence of the B-violating couplings and examine their contributions to the FCNC productions proceeding through the parton processes cg -> t, gg -> t c_bar, cg -> t\gamma, cg -> t Z and cg -> t h. We find that all these processes can be greatly enhanced relative to the R-parity preserving predictions. In the parameter space allowed by current experiments, all the production channels except cg ->t h can reach the 3-sigma sensitivity, in contrast to the R-parity preserving case in which only cg -> t can reach the 3-sigma sensitivity.Comment: version in PRD (discussions added

Formation of robust and completely tunable resonant photonic band gaps

We identify different types of the photonic band gaps (PBGs) of two dimensional magnetic photonic crystals (MPCs) consisting of arrays of magnetic cylinders and study the different tunability (by an external static magnetic field) of these PBGs. One type of the band gaps comes from infinitely degenerate flat bands and is closely related to those in the study of plasmonics. In addition, such PBGs are magnetically tunable and robust against position disorder. We calcualte the transmission of the PBG's and found excellent agreement with the results of the photonic band structure calculation. Positional disorder of the lattice structure affects the different types of PBGs differently.Comment: 4 pages, 5 figure