Multiplicity results for some nonlinear Schroedinger equations with potentials

We prove some multiplicity results for a nonlinear equation of Schroedinger type with potential function

Global bifurcation of homoclinic solutions of hamiltonian systems

We provide global bifurcation results for a class of nonlinear hamiltonian systemsComment: 25 page

The physiological response of Populus tremula x alba leaves to the down-regulation of PIP1 aquaporin gene expression under no water stress.

In order to study the role of PIP1 aquaporins in leaf water and CO2 transport, several lines of PIP1-deficient transgenic Populus tremula x alba were generated using a reverse genetic approach. These transgenic lines displayed no visible developmental or morphological phenotypes when grown under conditions of no water stress. Major photosynthetic parameters were also not affected by PIP1 down regulation. However, low levels of PIP1 expression resulted in greater leaf hydraulic resistance (an increase of 27%), which effectively implicated PIP1 role in water transport. Additionally, the expression level of PIP1 genes in the various transgenic lines was correlated with reductions in mesophyll conductance to CO2 (gm), suggesting that in poplar, these aquaporins influenced membrane permeability to CO2. Overall, although analysis showed that PIP1 genes contributed to the mass transfer of water and CO2 in poplar leaves, their down-regulation did not dramatically impair the physiological needs of this fast growing tree when cultivated under conditions of no stress

A MODEL OF PESTICIDE RESISTANCE AS A COMMON PROPERTY AND EXHAUSTIBLE RESOURCE

A dynamic farm production model analyzes the interaction between the externalities caused by pest mobility and the development of pesticide resistance, a nonrenewable resource, in the context of agricultural biotechnologies. The model measures the effect of farmers' myopic behavior and the impact of pest mobility on the path of resistance.biotechnology, common property resource, European Corn Borer, externalities, pesticide resistance, intertemporal optimization, Research and Development/Tech Change/Emerging Technologies,

OPTIMAL PESTICIDE USAGE WITH RESISTANCE AND ENDOGENOUS TECHNOLOGICAL CHANGE

This paper develops a model analyzing the first best policy for a social planner when pesticide use causes resistance, the level of pest infestation is heterogeneous among farmers, and the development of a backstop technology is an endogenous and uncertain process which depends on the cumulative amount of R&D effort.Crop Production/Industries,

MANAGING PEST RESISTANCE: THE POTENTIAL OF CROP ROTATIONS AND SHREDDING

The current debate over resistance management plans mandated by the Environmental Protection Agency for transgenic crops ignores management practices that are complementary to refuge schemes. A dynamic production model is developed that measures the costs and benefits of crop rotation and shredding in terms of delaying resistance to Bt corn.biotechnology, common property resource, crop rotation, European Corn Borer, externalities, insecticide resistance, integrated pest management, intertemporal optimization, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Land-Use Implications of the Changes in Energy Prices

Land Economics/Use, Resource /Energy Economics and Policy,

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,