PRAGMATISM vs RIGOUR: A Debate on the Resolution Of Disparate Analytical Data on Four Canadian Iron - Formation Reference Samples

The analytical data received in an inter-laboratory study of four Canadian reference samples were treated by two different methods in order to arrive at "usable values" for the concentration of each constituent. The first method ("Select Laboratories"), proposed by S. Abbey (S.A.), is based on the fact that some laboratories consistently produce better results than others. S.A. suggests an approach which permits isolation of results from such laboratories, calculation of a mean or a median of such results and use of one or the other as the concentration of a constituent. That approach involves a degree of subjectivity and S.A. attempts to demonstrate the validity of his approach by means of several tests applied to the results obtained for the four samples.     

The possible impacts on wheat production of a recurrence of the 1930s drought in the U.S. Great Plains

What would be the impacts on wheat production if the U.S. Great Plains were to suffer another severe, prolonged drought? The 1930s drought is chosen as a worst-case scenario, and two sets of crop-yield regression models are employed to simulate yields using actual 1932–40 weather values and assuming constant 1975 technology. The results are first compared to normal or expected yields in each of 53 crop reporting districts in order to determine the range and spatial variation in yield departures over the nine-year period. Assuming a 1976 crop area, wheat production levels are then calculated and aggregated to give Plains-wide estimates for each year. It is found that the sequence of 1930s weather results in continuous, prolonged declines in expected production. Plains-wide yields are below normal (on average about 9–14%) for nine consecutive years. In the poorest years, the impacts are areally widespread with about nine-tenths of the Plains experiencing yield declines. The spatial variation in yields is substantial, however, ranging from over 100% to below 40% of expected even in the poorest years. In the worst year (1936), simulated production is sharply reduced by about -25%, or 9.6 million metric tonnes. The cumulative deficit over the nine-year period is roughly equivalent to a full year's wheat production. The major conclusion is that a return of a 1930s-type drought would still inflict widespread, heavy damage on wheat production in the Great Plains.     

A crustal seismic velocity model for the UK, Ireland and surrounding seas

A regional model of the 3-D variation in seismic P -wave velocity structure in the crust of NW Europe has been compiled from wide-angle reflection/refraction profiles. Along each 2-D profile a velocity–depth function has been digitised at 5 km intervals. These 1-D velocity functions were mapped into three dimensions using ordinary kriging with weights determined to minimise the difference between digitised and interpolated values. An analysis of variograms of the digitised data suggested a radial isotropic weighting scheme was most appropriate. Horizontal dimensions of the model cells are optimised at 40 × 40 km and the vertical dimension at 1 km. The resulting model provides a higher resolution image of the 3-D variation in seismic velocity structure of the UK, Ireland and surrounding areas than existing models. The construction of the model through kriging allows the uncertainty in the velocity structure to be assessed. This uncertainty indicates the high density of data required to confidently interpolate the crustal velocity structure, and shows that for this region the velocity is poorly constrained for large areas away from the input data.