MANAGING EUROPEAN CORN BORER RESISTANCE TO BT CORN WITH DYNAMIC REFUGES

We develop a dynamic bioeconomic model of temporally optimal dynamic refuge recommendations for resistance management when a backstop technology arrives at a known date. The impact of the characteristics of the backstop on the use of the current technology, and the difference between static and dynamic refuges are examined.Crop Production/Industries,

TARGETING AND THE ECONOMICS OF CUMULATIVE WATERSHED EFFECTS

This study empirically investigates environmental benefits at the watershed level from conservation practices, which are typically non-linear. A conservation tillage adoption model is linked to the Soil and Water Assessment Tool model to examine the effectiveness of various conservation policies aimed at improving water quality in an Iowa watershed.Environmental Economics and Policy,

MANAGING THE RISK OF EUROPEAN CORN BORER RESISTANCE TO TRANSGENIC CORN: AN ASSESSMENT OF CONTROVERSIAL REFUGE RECOMMENDATIONS

A bioeconomic model is developed to evaluate the tradeoff between the risk of resistance and increased productivity when refuge is planted in conjunction with transgenic pesticidal corn. The model is used to evaluate controversial refuge recommendations when producers are allowed to treat refuge in years of high pest pressure.Productivity Analysis, Research and Development/Tech Change/Emerging Technologies, Risk and Uncertainty,

Cac Versus Incentive-Based Instruments in Agriculture: The Case of the Conservation Reserve Program

In this paper, we examine command-and-control (CAC) policies and market-based instruments (MBI) in the context of the Conservation Reserve Program (CRP). The CRP, an MBI in the form of subsidies, is by far the largest agro-environmental policy implemented to date. We compare the environmental performance of the CRP as implemented to a few counterfactual CAC polices using EPIC (Environmental Policy Integrated Climate), a bio-physical simulation model. In the context of multiple environmental indicators, no policy alternative emerges as a clear winner. The importance of the choice and design of CAC policies is emphasized. Keywords: command-and-control policy, Conservation Reserve Program, market-based instrument.

Communication Through Motion: Legibility of Multi-Robot Systems

The interaction between a user and a multi-robot system in a shared environment is a relatively uncharted topic. But, as these types of systems will increase in the future years, an efficient way of communication is necessary. To this aim, it is interesting to discover if a multi-robot system can communicate its intentions exploiting only some motion-variables, which are characteristics of the motion of the robots. This study is about the legibility of a multi-robot system: In particular, we focus on the influence of these motion-variables on the legibility of more than one group of robots that move in a shared environment with the user. These motion-variables are: Trajectory, dispersion and stiffness. They are generally used to define the motion of a group of mobile robots. Trajectory and dispersion were found relevant for the correctness of the communication between the user and the multi-robot system, while stiffness was found relevant for the rapidity of communication. The analysis of the influence of the motion-variables was carried out with an ANOVA (analysis of variance) based on a series of data coming from an experimental campaign conducted in a virtual reality set-up

Observation and Spectroscopy of a Two-Electron Wigner Molecule in an Ultra-Clean Carbon Nanotube

Coulomb interactions can have a decisive effect on the ground state of electronic systems. The simplest system in which interactions can play an interesting role is that of two electrons on a string. In the presence of strong interactions the two electrons are predicted to form a Wigner molecule, separating to the ends of the string due to their mutual repulsion. This spatial structure is believed to be clearly imprinted on the energy spectrum, yet to date a direct measurement of such a spectrum in a controllable one-dimensional setting is still missing. Here we use an ultra-clean suspended carbon nanotube to realize this system in a tunable potential. Using tunneling spectroscopy we measure the excitation spectra of two interacting carriers, electrons or holes, and identify seven low-energy states characterized by their spin and isospin quantum numbers. These states fall into two multiplets according to their exchange symmetries. The formation of a strongly-interacting Wigner molecule is evident from the small energy splitting measured between the two multiplets, that is quenched by an order of magnitude compared to the non-interacting value. Our ability to tune the two-electron state in space and to study it for both electrons and holes provides an unambiguous demonstration of the fundamental Wigner molecule state.Comment: SP and FK contributed equally to this wor

Managing European Corn Borer Resistance to Bt Corn with Dynamic Refuges

Genetically engineered Bt (Bacillus thuringiensis) corn provides farmers with a new tool for controlling the European corn borer (ECB). The high efficacy and potential rapid adoption of Bt corn has raised concerns that the ECB will develop resistance to Bt. The Environmental Protection Agency has responded to these concerns by requiring farmers to plant refuge corn. Current refuge requirements are based on models that do not consider the value of dynamically varying refuge in response to increased scarcity and diminished control over time or the importance of backstop technologies currently being developed. The purpose of this paper is to evaluate dynamically optimal refuge requirements with the arrival of alternative backstop technologies and to compare the results to an optimal static refuge policy. The results show that a dynamically optimal refuge requirement only provides modest benefits above a static optimum. The results also show how the type of backstop technology and characteristics of ECB population dynamics affect the optimal refuge requirement

Privatizing Ecosystem Services: Water Quality Effects from a Carbon Market

Resource /Energy Economics and Policy, Q25,

Biopolymer gels with "physical" cross-links: gelation kinetics, aging, heterogeneous dynamics, and macroscopic mechanical properties

Alginate is a natural biopolymer that forms, in the presence of divalent cations, ionic-bound gels typifying a large class of biological gels stabilized by non-covalent cross-links, and displaying a consistent restructuring kinetics. We investigate the kinetics of formation and aging of alginate gels by slow permeation of a curing CaCl2 agent by means of photon correlation imaging, a novel optical technique that allows obtaining the microscopic dynamics of the sample, while retaining at the same time the spatial resolution of imaging techniques. Specifically, the gelling kinetics displays a peculiar non-diffusive behavior, and the subsequent restructuring of the gel structure shares several features in common with the aging of colloidal gels, in particular for what concerns the occurrence of heterogeneous dynamics effects. A comparative analysis of the gel macroscopic mechanical properties at different aging stages further highlights distinctive effects arising from the non-permanent nature of the bonds