Nonpoint source pollution, space, time, and asymmetric information, a deposit refund approach

The incorporation of space allows the establishment of a more precise relationship between a contaminating input, a contaminating byproduct and emissions that reach the final receptor. However, the presence of asymmetric information impedes the implementation of the first-best policy. As a solution to this problem a site specific deposit refund system for the contaminating input and the contaminating byproduct are proposed. Moreover, the utilization of a successive optimization technique first over space and second over time enables definition of the optimal intertemporal site specific deposit refund system.nonpoint source pollution; spatial economics; deposit refund system; asymmetric information

Land Development and Pigouvian Taxes: The Case of Peatland

In this paper the determination of an optimal Pigouvian tax for a competitive firm when a negative production externality is present concurrent with the development of land for production purposes is analyzed within a dynamic framework. Conditions are established for a convex social net return function where a Pigouvian tax is not required or where the imposition of a Pigouvian tax leads to the decision not to develop the land at all. In the case of a concave social net return function the Pigouvian tax is either a linear or a nonlinear tax on the private net return

Land allocation under consideration of weather-induced crop yield variations: Decision support by a crop yield simulation and risk analysis model (ERM)

This paper presents a PC-based crop yield simulation and risk analysis model for a single farm, with the weather as the stochastic component. The ERM allows the calculation of the distribution of the farm net returns for a specific crop-rotation plan. Compared to other risk analysis models, the ERM does not ask the user to supply recorded farm data related to the past nor does it employ a specific utility function. In the ERM, the farm-specific context is included in having the farmer specify the minimum, maximum and average crop yield for four out of 17 analysed crops. The application of the ERM to an arable farm is demonstrate

The Efficiency of Direct Payments versus Tax Reductions under Uncertainty

This paper analyzes the optimal behavior of farmers in the presence of direct payments and uncertainty. In an empirical analysis for Switzerland, it confirms previously obtained theoretical results and determines the magnitude of the theoretical predicted effects. The results show that direct payments increase agricultural production between 3.7% to 4.8%. Alternatively to direct payments, the production effect of tax reductions is evaluated in order to determine its magnitude. The empirical analysis corroborates the theoretical results of the literature and demonstrates that tax reductions are also distorting, but to a substantially lesser degree if losses are not offset. However, tax reductions, independently whether losses are offset or not, lead to higher government spending than pure direct payments.Uncertainty; Direct Payments; Income Tax; Reductions; Agriculture

Relationships between CYP2D6 phenotype, breast cancer and hot flushes in women at high risk of breast cancer receiving prophylactic tamoxifen: results from the IBIS-I trial

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Geometry of lipid vesicle adhesion

The adhesion of a lipid membrane vesicle to a fixed substrate is examined from a geometrical point of view. This vesicle is described by the Helfrich hamiltonian quadratic in mean curvature; it interacts by contact with the substrate, with an interaction energy proportional to the area of contact. We identify the constraints on the geometry at the boundary of the shared surface. The result is interpreted in terms of the balance of the force normal to this boundary. No assumptions are made either on the symmetry of the vesicle or on that of the substrate. The strong bonding limit as well as the effect of curvature asymmetry on the boundary are discussed.Comment: 7 pages, some major changes in sections III and IV, version published in Physical Review

Mycobacterium tuberculosis MycP1 Protease Plays a Dual Role in Regulation of ESX-1 Secretion and Virulence

SummaryMycobacterium tuberculosis uses the ESX-1 secretion system to deliver virulence proteins during infection of host cells. Here we report a mechanism of posttranscriptional control of ESX-1 mediated by MycP1, a M. tuberculosis serine protease. We show that MycP1 is required for ESX-1 secretion but that, unexpectedly, genetic inactivation of MycP1 protease activity increases secretion of ESX-1 substrates. We demonstrate that EspB, an ESX-1 substrate required for secretion, is a target of MycP1 in vitro and in vivo. During macrophage infection, an inactive MycP1 protease mutant causes hyperactivation of ESX-1-stimulated innate signaling pathways. MycP1 is required for growth in mice during acute infection, while loss of its protease activity leads to attenuated virulence during chronic infection. As the key ESX-1 substrates ESAT-6 and CFP-10 are highly immunogenic, fine-tuning of their secretion by MycP1 may balance virulence and immune detection and be essential for successful maintenance of long-term M. tuberculosis infection

Modelling Soil Erosion, Sediment Transport and Closely Related Hydrological Processes (Proceedings of a symposium held at Vienna

Abstract The validity of the EPIC (Erosion/Productivity Impact Calculator) model was tested for a site in the undulating ground moraine region of central Switzerland which has uniform soil and relief conditions (silt loam, 10% slope). The EPIC weather generator was used to generate long sequences of synthetic weather with the characteristics of the present-day. Based on these data, soil losses associated with different crop rotations and cultivation techniques for variable initial soil depths were simulated. The results are employed in an economic decision model where the choice of crops, associated with distinct erosion rates, allows the farmer to control soil loss. A first evaluation of the economic model indicates that the financial losses, attributed to soil erosion, are fairly small and hardly influence the long-term optimal behaviour of the farmer. Thus, there is a strong case for intervention by the government provided that society places a high value on the existence of non-eroded soil

The Role of Bilayer Tilt Difference in Equilibrium Membrane Shapes

Lipid bilayer membranes below their main transition have two tilt order parameters, corresponding to the two monolayers. These two tilts may be strongly coupled to membrane shape but only weakly coupled to each other. We discuss some implications of this observation for rippled and saddle phases, bilayer tubules, and bicontinuous phases. Tilt difference introduces a length scale into the elastic theory of tilted fluid membranes. It can drive an instability of the flat phase; it also provides a simple mechanism for the spontaneous breaking of inversion symmetry seen in some recent experiments.Comment: Latex file; .ps available at http://dept.physics.upenn.edu/~nelson/saddle.p