Conformational studies of various hemoglobins by natural-abundance 13C NMR spectroscopy

Studies of variously liganded hemoglobins (both from human and rabbit) by natural-abundance 13C NMR spectroscopy have revealed apparent conformational differences that have been interpreted on the basis of two quaternary structures for the α2ß2 tetramer, and variable tertiary structures for the individual α and ß subunits. In solution, rabbit hemoglobins appear to have somewhat more flexibility than human hemoglobins

Cost and Efficiency in Alberta Dairy Production

This study investigates the relationships between farm size, milk yield, cost of production, and technical efficiency in the Alberta dairy industry. Estimates of a stochastic production frontier are obtained with two alternative methods; an iterative "average frontier: (AF) procedure and a maximum-likelihood composed error (CE) term method. An index of technical efficiency is calculated for every herd in the sample, with the AF method resulting in an average efficiency ratio of 85 percent, and the CE method producing an average efficiency ratio of 83 percent. Regressions of production cost on milk output, herd size, and efficiency are used to test for the effects of size economies, yield economies, and technical efficiency on production cost. These results suggest that herd expansion, on average, would lower the average cost of production throughout the province. Romain and Lambert use a similar method in a study of Quebec and Ontario dairy farmers which shows a limited potential to exploit economies of herd size. While not a formal test of the similarity of the two industries, the results of this study indicate a significant difference between the optimal structure of dairy production in Alberta and Quebec. Such regional differences will have important implications for the possible reapportionment of the national milk market, whether by regulatory or free-market mechanisms.Livestock Production/Industries,

The infinite line pressure probe

The infinite line pressure probe provides a means for measuring high frequency fluctuating pressures in difficult environments. A properly designed infinite line probe does not resonate; thus its frequency response is not limited by acoustic resonance in the probe tubing, as in conventional probes. The characteristics of infinite line pressure probes are reviewed and some applications in turbine engine research are described. A probe with a flat-oval cross section, permitting a constant-impedance pressure transducer installation, is described. Techniques for predicting the frequency response of probes with both circular and flat-oval cross sections are also cited