AN INVERSE DEMAND APPROACH TO RECREATION FISHING SITE CHOICE AND IMPLIED MARGINAL VALUES

An alternative methodology for determining marginal willingness to pay values for recreational fishing trips is developed based on inverse demand systems and the distance function. Our empirical application uses joint estimation of several species-specific site equations from a recreation fishing data set. Results are compared to a random utility model.Resource /Energy Economics and Policy,

Application of dielectric constant measurements to radar imagery interpretation

The author has identified the following significant results. Although it is readily recognized that there is a need for ground truth to provide adequate guidance for remote sensing data interpretation, it is noted that, in terms of radar remote sensing, this ground truth is often inadequate. It is necessary to make basic electrical and physical measurements of the surface and to some depth below it. A brief outline is presented of a ground truth scheme which uses measurements of the dielectric constant. Two portable instruments were designed specifically for this purpose; these were: (1) a Q-meter for measurement of dielectric constant and loss tangent; and (2) an instrument to measure electrical properties of the two operating frequencies of the imaging radar. Although extensive data are lacking, several general cases of radar-earth surface and interaction are described; also, examples of radar imagery and some data on ice and snow are presented. It is concluded that the next logical step is to begin to quantify the radar ground truth in preparation for machine interpretation and automatic data processing of the radar imagery

EMPIRICAL SPECIFICATION REQUIREMENTS FOR TWO-CONSTRAINT MODELS OF RECREATION DEMAND

Theoretical restrictions implied by the two-constraint recreation demand model are developed. The structure necessary to specify empirical models shows that most current models of recreation incorporate time in a manner inconsistent with theory. Results are applicable to all recreationists and are particularly useful to those with endogenous marginal values of time.Research Methods/ Statistical Methods, Resource /Energy Economics and Policy,

Gravitational Radiation from Black Hole Binaries in Globular Clusters

A populations of stellar mass black hole binaries may exist in globular clusters. The dynamics of globular cluster evolution imply that there may be at most one black hole binary is a globular cluster. The population of binaries are expected to have orbital periods greater than a few hours and to have a thermal distribution of eccentricities. In the LISA band, the gravitational wave signal from these binaries will consist of several of the higher harmonics of the orbital frequency. A Monte Carlo simulation of the galactic globular cluster system indicates that LISA will detect binaries in 10 % of the clusters with an angular resolution sufficient to identify the host cluster of the binary.Comment: 7 pages, 2 eps figures, uses iopart styl

AGRICULTURAL ADAPTATION TO URBANIZATION IN SOUTHEASTERN PENNSYLVANIA

Most agricultural output in the northeastern United States comes from counties that have experienced significant development. A mail survey, with 300 responses, was conducted in southeastern Pennsylvania to determine farmer adaptation to urbanization in this region. Despite development, traditional agriculture still predominates. Changes in land use were examined using multinomial logit models. Results show that change in population density and farm preservation policies have an influence, as increased population density reduced total land operated and having land in an agricultural security area increased it. Both differential assessment and agricultural security areas increased the cultivation of traditional, land extensive crops.Agricultural and Food Policy, Community/Rural/Urban Development,

LOCATIONAL EFFECTS OF URBANIZATION ON AGRICULTURE IN SOUTHEASTERN PENNSYLVANIA

Most agricultural output in the northeastern United States comes from counties that have experienced significant development. A mail survey, with 300 responses, was conducted in southeastern Pennsylvania to determine farmer adaptation to urbanization in this region. Despite development, traditional agriculture still predominates. Changes in land use were examined using multinomial logit models. Results show that changes in population density and farm preservation policies have an influence, as increased population density reduced total land operated and having land in an agricultural security area increased it. Other measures of urbanization, such as proximity to a city or inter-state highway had no statistically significant effect on farm practices. Keywords: Agricultural adaptation, rural development, off-farm income, urbanization, land useAgricultural adaptation, rural development, off-farm income, urbanization, land use, Land Economics/Use,

NATIVE AND EUROPEAN HAPLOTYPES OF \u3ci\u3ePHRAGMITES AUSTRALIS\u3c/i\u3e (COMMON REED) IN THE CENTRAL PLATTE RIVER, NEBRASKA

Phragmites australis (common reed) is known to have occurred along the Platte River historically, but recent rapid increases in both distribution and density have begun to impact habitat for migrating sandhill cranes and nesting piping plovers and least terns. Invasiveness in Phragmites has been associated with the incursion of a European genotype (haplotype M) in other areas; determining the genotype of Phragmites along the central Platte River has implications for proper management of the river system. In 2008 we sampled Phragmites patches along the central Platte River from Lexington to Chapman, NE, stratified by bridge segments, to determine the current distribution of haplotype E (native) and haplotype M genotypes. In addition, we did a retrospective analysis of historical Phragmites collections from the central Platte watershed (1902- 2006) at the Bessey Herbarium. Fresh tissue from the 2008 survey and dried tissue from the herbarium specimens were classified as haplotype M or E using the restriction fragment length polymorphism procedure. The European haplotype was predominant in the 2008 samples: only 14 Phragmites shoots were identified as native haplotype E; 224 were non-native haplotype M. The retrospective analysis revealed primarily native haplotype individuals. Only collections made in Lancaster County, near Lincoln, NE, were haplotype M, and the earliest of these was collected in 1973

Factors affecting post-control reinvasion by seed of an invasive species, \u3ci\u3ePhragmites australis\u3c/i\u3e, in the central Platte River, Nebraska

Invasive plants, such as Phragmites australis, can profoundly affect channel environments of large rivers by stabilizing sediments and altering water flows. Invasive plant removal is considered necessary where restoration of dynamic channels is needed to provide critical habitat for species of conservation concern. However, these programs are widely reported to be inefficient. Post-control reinvasion is frequent, suggesting increased attention is needed to prevent seed regeneration. To develop more effective responses to this invader in the Central Platte River (Nebraska,USA), we investigated several aspects of Phragmites seed ecology potentially linked to post-control reinvasion, in comparison to other common species: extent of viable seed production, importance of water transport, and regeneration responses to hydrology. We observed that although Phragmites seed does not mature until very late in the ice-free season, populations produce significant amounts of viable seed (\u3e50 %of filled seed). Most seed transported via water in the Platte River are invasive perennial species, although Phragmites abundances are much lower than species such as Lythrum salicaria, Cyperus esculentus and Phalaris arundinacea. Seed regeneration of Phragmites varies greatly depending on hydrology, especially timing of water level changes. Flood events coinciding with the beginning of seedling emergence reduced establishment by as much as 59 % compared to flood events that occurred a few weeks later. Results of these investigations suggest that prevention of seed set (i.e., by removal of flowering culms) should be a priority in vegetation stands not being treated annually. After seeds are in the seedbank, preventing reinvasion using prescribed flooding has a low chance of success given that Phragmites can regenerate in a wide variety of hydrologic microsites

ESTIMATING THE OPPORTUNITY COST OF RECREATION TIME IN AN INTEGRABLE 2-CONSTRAINT COUNT DEMAND MODEL

How researchers treat the opportunity cost of time substantially influences recreation demand parameter and welfare estimates. This paper presents a utility-theoretic and implementable approach, estimating the shadow value of time jointly with recreation demands for coastal activities, using a generalization of the semilog demand system in a two-constraint model.Consumer/Household Economics, Demand and Price Analysis,

Transmission electron microscopy characterization of microstructural features of Al-Li-Cu alloys

A transmission electron microscopy (TEM) examination of aluminum-lithium-copper alloys was conducted. The principal purpose is to characterize the nature, size, and distribution of stringer particles which result from the powder metallurgy (P/M) processing of these alloys. Microstructural features associated with the stringer particles are reported that help explain the stress corrosion susceptibility of the powder metallurgy-processed Al-Li-Cu alloys. In addition, matrix precipitation events are documented for a variety of heat treatments and process variations. Hot rolling is observed to significant alter the nature of matrix precipitation, and the observations are correlated with concomitant mechanical property variations