A graph efficiency multiproduct model of corn/livestock farming: Accounting for nitrate pollution

This paper estimates a non-parametric production frontier for a population of 117 corn/livestock farms in the Corn Belt region in 1987, employing a hyperbolic graph efficiency approach. There are 7 outputs, 39 variable inputs, 4 fixed inputs, and one bad input (residual nitrogen). Three graph efficiency models are estimated. A profit maximization model is specified to estimate a production frontier constrained only by the fixed factors. Two other models involving tax constraints are also estimated. One involves a tax directly on nitrogen and the other involves a tax directly on residual nitrogen, making the disposal of residual nitrogen costly. The nitrogen tax constraint is more effective in reducing residual nitrogen loadings and causes a larger reduction in income than the residual tax constraint.     

Recent syntheses and reactions of cyclic imidic esters

Δ²-Oxazolines and 4H-5,6-dihydrooxazines are readily obtainable from carboxylic acids and 2- or 3-amino alcohols by gas-phase dehydration, and 4H-dihydrooxazines can also be obtained by condensation of N-(hydroxymethyl) carboxamides with olefins. These cyclic imidic esters undergo reactions in which the ring is cleaved; these reactions include a new type of polymerization. The behavior of alkyl groups in position 2 and the cyclodditions in the 2,3-position also have been studied. Reactions in side chains on position 2 and addition experiments on the sulfur analogues of the cyclic imidic esters are also reported. A table shows the principal infrared bands of substituted Δ²-oxazolines.     

Splitting‐characterizations of the Papangelou process

For point processes we establish a link between integration‐by‐parts‐ and splitting‐formulas which can also be considered as integration‐by‐parts‐formulas of a new type. First we characterize finite Papangelou processes in terms of their splitting kernels. The main part then consists in extending these results to the case of infinitely extended Papangelou and, in particular, Pólya and Gibbs processes.     

Two new eudesmane derivatives from Verbesina virginica

<正>Two new eudesmane derivatives were isolated from the leaves and flowers of Verbesina virginica,along with the known 6-O-β-E -p-coumaroyl-4α-hydroxyeudesmane(1).Their structures were determined as 6-O-β-Z-p-coumaroyl-4α-hydroxyeudesmane(2) and 6-O-α-E-p-coumaroyl-1β-4α-dihydroxyeudesmane(3) by spectroscopic methods.     

Zur Untersuchung der Drogen

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