USING OPTIMAL CONTROL TO CHARACTERIZE THE ECONOMIC AND ECOLOGICAL IMPLICATIONS OF SPATIAL EXTERNALITIES

This study uses optimal control theory to examine the dynamic features of agricultural landscapes characterized by spatial externalites. A stylized system of agricultural production and groundwater flow is used to illustrate how spatial externalities affect land use decisions over time. Policy alternatives are also considered.Environmental Economics and Policy,

Modeling Recreational Amenities in an Urban Setting: Location, Congestion, and Substitution Effects

In this article, we introduce a recreational amenity—a greenbelt park—into a simple urban economic model. For multiple possible park placements, we solve for the associated equilibrium urban structure, including the equilibrium rent gradient, city boundary, total number of park visits, the overall utility level, and total vehicle miles traveled. We examine how these change with alternative park placement sites. We then show how two modifications of the basic model—allowing congestion at the site to affect site quality, and introducing the possibility of a substitute site at the city’s periphery—affect our conclusions about how greenbelt location influences urban structure.urban structure, greenbelt, congestion, Research and Development/Tech Change/Emerging Technologies,

URBAN PLANNING AND THE LOCATION OF ENVIRONMENTAL AMENITIES

In this paper, we use a simple urban economic model to study how choosing park locations within a city might contribute towards urban planning goals. For multiple possible park placements, we solve for the associated equilibrium urban structure, including the equilibrium rent gradient, city boundary, total number of park visits, the overall utility level, and total vehicle miles traveled. We then examine how these change with alternative park placement sites. We find that, as a prescription for reducing urban sprawl, park provision has mixed results. When placed close to the central business district, the park can result in an increase in inner city housing density; such placement could help ameliorate problems of commuter traffic congestion related to urban sprawl. Parks placed further out toward the periphery, although consistent with improved accessibility and utility maximization, have the opposite effect pulling residents away from the central business district and thereby likely worsening the congestion problem related to commuter traffic.Community/Rural/Urban Development, Environmental Economics and Policy,

A SPATIAL ANALYSIS OF THE ECONOMIC AND ECOLOGICAL EFFICACY OF LAND RETIREMENT

Most land management policies, such as land retirement, have multiple objectives. This study uses a cellular automata simulation model to explore how various spatial characteristics of land parcels on a hypothetical landscape contribute to the efficacy of land retirement in the presence of multiple retirement objectives- hydrological improvement, habitat improvement, and cost. Statistical analysis of the simulation results is used to tie particular spatial characteristics back to achievement of the three distinct objectives. In order to combine the three objectives into a measure that allows decision-makers to rank the desirability of different retirement strategies, linear and nonlinear goal programming frameworks are introduced. These frameworks are explored to determine what each implies about the tradeoffs that must be made among objectives and among the spatial land parcel characteristics that contribute to those objectives.Land Economics/Use,

The preferentially magnified active nucleus in IRAS F10214+4724 - II. Spatially resolved cold molecular gas

We present JVLA observations of the cold (CO (1-0)) molecular gas in IRAS F10214+4724, a lensed ULIRG at z=2.3 with an obscured active nucleus. The galaxy is spatially and spectrally well-resolved in the CO (1-0) emission line. A CO (1-0) counter-image is detected at the 3-sigma level. Five of the 42 km/s channels (with >5-sigma detections) are mapped back into the source plane and their total magnification posterior PDFs sampled. This reveals a roughly linear arrangement, tentatively a rotating disk. We derive a molecular gas mass of M_gas = 1.2 +- 0.2 x 10^10 M_sun, assuming a ULIRG L_{CO}-to-M_{gas} conversion ratio of \alpha = 0.8 M_sun / (K km/s pc^2) that agrees well with the derived range of \alpha = 0.3 - 1.3 for separate dynamical mass estimates at assumed inclinations of i = 90 - 30 degrees. Based on the AGN and CO (1-0) peak emission positions and the lens model, we predict a distortion of the CO Spectral Line Energy Distribution (SLED) where higher order J lines that may be partially excited by AGN heating will be preferentially lensed owing to their smaller solid angles and closer proximity to the AGN and therefore the cusp of the caustic. Comparison with other lensing inversion results shows that the narrow line region and AGN radio core in IRAS F10214+4724 are preferentially lensed by a factor >~ 3 and 11 respectively, relative to the molecular gas emission. This distorts the global continuum emission Spectral Energy Distribution (SED) and suggests caution in unsophisticated uses of IRAS F10214+4724 as an archetype high-redshift ULIRG. We explore two Large Velocity Gradient (LVG) models, incorporating spatial CO (1-0) and (3-2) information and present tentative evidence for an extended, low excitation cold gas component that implies that the total molecular gas mass in IRAS F10214+4724 is a factor >~2 greater than that calculated using spatially unresolved CO observations.Comment: Dedicated to Steve Rawlings. Accepted for publication in MNRAS. 16 pages, 11 figure

The changes in leaf reflectance of sugar maple seedlings (Acer saccharum Marsh) in response to heavy metal stress

The effects of heavy metal stress on leaf reflectance of sugar maple seedlings (Acer saccharum Marsh) are examined. It is found that sugar maple seedlings treated with anomalous amounts of heavy metals in the rooting medium exhibited an increased leaf reflectance over the entire range of investigated wavelengths, from 475 to 1650 nm. These results conform to those of a previous investigation in the wavelengths from 475 to 660nm, but tend to contradict the previous study in the near infrared wavelengths from 1000 to 1650nm. The differences may possible be due to different water regimes in the two investigations