A GLOBAL MODEL OF CLIMATE CHANGE IMPACTS ON TIMBER MARKETS

Several papers have now estimated the impact of climate change on national timber markets, but few studies have measured impacts globally. Further, the literature on impacts has focused heavily on changes in productivity and has not integrated movements of biomes as well. Here, a dynamic model of ecological change and economic change is developed to capture the impact of climate change on world timber markets. Climate change is predicted to increase global timber production as producers in low-mid latitude forests react quickly with more productive short-rotation plantations, driving down timber prices. Producers in mid-high latitude forests, in contrast, are likely to be hurt by the lower prices, dieback, and slower productivity increases because of long-rotation species. Consumers in all regions benefit from the lower prices, and the overall impacts of climate change in timber markets are expected to be beneficial, increasing welfare in those markets from 2% to 8%.Resource /Energy Economics and Policy,

Structure and orientation of lung surfactant SP-C and L-alpha-dipalmitoylphosphatidylcholine in aqueous monolayers

SP-C, a pulmonary surfactant-specific protein, aids the spreading of the main surfactant phospholipid L-alpha-dipalmitoylphosphatidylcholine (DPPC) across air/water interfaces, a process that has possible implications for in vivo function. To understand the molecular mechanism of this process, we have used external infrared reflection-absorption spectroscopy (IRRAS) to determine DPPC acyl chain conformation and orientation as well as SP-C secondary structure and helix tilt angle in mixed DPPC/SP-C monolayers in situ at the air/water interface. The SP-C helix tilt angle changed from approximately 24 degrees to the interface normal in lipid bilayers to approximately 70 degrees in the mixed monolayer films, whereas the acyl chain tilt angle of DPPC decreased from approximately 26 degrees in pure lipid monolayers (comparable to bilayers) to approximately 10 degrees in the mixed monolayer films. The protein acts as a "hydrophobic lever" by maximizing its interactions with the lipid acyl chains while simultaneously permitting the lipids to remain conformationally ordered. In addition to providing a reasonable molecular mechanism for protein-aided spreading of ordered lipids, these measurements constitute the first quantitative determination of SP-C orientation in Langmuir films, a paradigm widely used to simulate processes at the air/alveolar interface

The steady flow between reservoirs with different density and level through a contraction

This paper presents a complete analytical solution of steady gravity flow between two reservoirs connected by a channel of slowly varying breadth and containing fluids of different densities and levels. The hydrostatic approximation is used and dissipation is neglected. It is shown that seven different regimes are possible depending on the value of the parameter δ = γ/ε, which is the ratio of relative lighter and denser reservoir level difference, γ, to positive relative density difference, ε. The exact solution of the problem is obtained for all these regimes. If the level of the heavier fluid reservoir is higher than the level of lighter fluid reservoir, δ ≤ 0, then the denser fluid plunges under the lighter motionless fluid. If δ ≥ 1, the lighter fluid runs up on a wedge of the motionless denser fluid. If 0 \u3c δ \u3c 1, two-directional exchange flow occurs. The exact analytical expressions for layer discharges for the entire range of the parameters ε and δ are found and discussed. Wood\u27s (1970) experimental data with nonsmall ε are in good agreement with the theory. When ε → 0 an exchange regime exists as long as γ → 0 to keep their ratio between 0 and 1, 1 \u3e γ/ε \u3e 0. At this limit the existence of an exchange flow and the solution depend only on the ratio γ/ε, not the values of γ and ε individually, and the Boussinesq approximation can be used. Some examples of application of the theory to prediction of mass and volume transport through a contraction for steady and quasi-steady flows are given