AN OPERATIONAL APPROACH FOR EVALUATING INVESTMENT RISK: AN APPLICATION TO THE NO-TILL TRANSITION

Roy’s safety-first rule is used to provide measures popular with farmers of short and long term business risk associated with various no-till transition strategies over an investment horizon. The short run rule provided more sensitivity to inter-year financial risk than other commonly used criteria. Results revealed that speed of adoption influenced the probability of successful transition more than did the sequence of drill acquisition methods. Higher equity and larger farms had a greater chance of transition success. Slow acreage expansion with a custom or rental drill reduces risk until a no-till yield penalty is eliminated.Investment risk, Monte Carlo simulation, no-till, rent- purchase, risk, safety-first, technology adoption, transition strategy

ENVIRONMENTAL AND ECONOMIC IMPACTS OF AGRICULTURAL POLICY REFORM: AN INTERREGIONAL COMPARISON

Mathematical programming results revealed that moving toward more flexible agricultural policies would generate substantial economic and environmental gains in a North Carolina diversified cropping region. But in a Washington-Idaho dryland grains region, only the use of relatively new and sometimes problematic alternative cropping systems permitted environmental and economic gains under policy reform. In both regions, a recoupling policy, which links government payments to resource-conserving farming practices, was needed to protect environmental quality when market prices for program crops were high.Agrichemical leaching, Agricultural policy, Alternative agriculture, Erosion, Mathematical programming, Agricultural and Food Policy,

On higher derivative corrections to Wess-Zumino and Tachyonic actions in type II super string theory

We evaluate in detail the string scattering amplitude to compute different interactions of two massless scalars, one tachyon and one closed string Ramond-Ramond field in type II super string theory. In particular we find two scalar field and two tachyon couplings to all orders of $\alpha'$ up to on-shell ambiguity. We then obtain the momentum expansion of this amplitude and apply this infinite number of couplings to actually check that the infinite number of tachyon poles of S-matrix element of this amplitude for the $p=n$ case (where $p$ is the spatial dimension of a D$_p$-brane and $n$ is the rank of a Ramond-Ramond field strength) to all orders of $\alpha'$ is precisely equal to the infinite number of tachyon poles of the field theory. In addition to confirming the couplings of closed string Ramond-Ramond field to the world-volume gauge field and scalar fields including commutators, we also propose an extension of the Wess-Zumino action which naturally reproduces these new couplings in field theory such that they could be confirmed with direct S-matrix computations. Finally we show that the infinite number of massless poles and contact terms of this amplitude for the $p=n+1$ case can be reproduced by Chern-Simons, higher derivative corrections of the Wess-Zumino and symmetrized trace tachyon DBI actions.Comment: 51 pages, some refs and comments added, typos are removed. Almost all ambiguities in BPS and non-BPS effective actions have been addresse

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,

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,

The Physical Properties of LBGs at z>5: Outflows and the "pre-enrichment problem"

We discuss the properties of Lyman Break galaxies (LBGs) at z>5 as determined from disparate fields covering approximately 500 sq. arcmin. While the broad characteristics of the LBG population has been discussed extensively in the literature, such as luminosity functions and clustering amplitude, we focus on the detailed physical properties of the sources in this large survey (>100 with spectroscopic redshifts). Specifically, we discuss ensemble mass estimates, stellar mass surface densities, core phase space densities, star-formation intensities, characteristics of their stellar populations, etc as obtained from multi-wavelength data (rest-frame UV through optical) for a subsample of these galaxies. In particular, we focus on evidence that these galaxies drive vigorous outflows and speculate that this population may solve the so-called ``pre-enrichment problem''. The general picture that emerges from these studies is that these galaxies, observed about 1 Gyr after the Big Bang, have properties consistent with being the progenitors of the densest stellar systems in the local Universe -- the centers of old bulges and early type galaxies.Comment: 4 pages, to appear in "Pathways Through an Eclectic Universe", J. H. Knappen, T. J. Mahoney, and A. Vazedekis (Eds.), ASP Conf. Ser., 200

Qualitative Analysis of Polycycles in Filippov Systems

In this paper, we are concerned about the qualitative behaviour of planar Filippov systems around some typical minimal sets, namely, polycycles. In the smooth context, a polycycle is a simple closed curve composed by a collection of singularities and regular orbits, inducing a first return map. Here, this concept is extended to Filippov systems by allowing typical singularities lying on the switching manifold. Our main goal consists in developing a method to investigate the unfolding of polycycles in Filippov systems. In addition, we applied this method to describe bifurcation diagrams of Filippov systems around certain polycycles

THE ROLE OF ENVIRONMENTAL EDUCATION IN PREDICTING ADOPTION OF WIND EROSION CONTROL PRACTICES

Logit and ordered probit analyses were used to identify factors associated with reduced tillage adoption, continuous spring cropping, and the number of changes made in response to wind erosion. Contrary to previous results for water erosion control, simple perception of a wind erosion problem or membership in a particular socioeconomic category did not significantly explain adoption of wind erosion control practices, but participating in a targeted educational program did. This educational program: (a) highlighted the threats of wind erosion to human health and to soil productivity, and (b) described specific potentially profitable farming practices for solving the wind erosion problem.Environmental Economics and Policy,

The Sweet Smell of Subsidies Revisited

Agricultural and Food Policy,