Effect of Prices, Traits and Market Structure on Corn Seeding Density

Recent agronomic research finds that economically optimal seeding densities have likely increased for many Midwestern corn farmers as a result of genetic improvements including new GM traits such as Bt corn and herbicide tolerance. We derive a per acre demand model for hybrid seed corn to examine the determinants of corn seeding densities and estimate the model using a large data set of individual farmer seed corn purchases. Current results identify factors other than prices affecting farmer corn seeding densities. Among these factors are the GM trait of the seed corn, measures of the local seed corn market structure, seed purchase source and intended end use. We interpret these effects in terms of information effects—farmers with more/better access to the latest agronomic research indicating that recommended seeding densities should be increased tend to plant corn at higher densities.hybrid seed corn, Bt corn, herbicide tolerance, Herfindahl index, corn borer, rootworm, hyperbolic yield model, Agribusiness, Crop Production/Industries, Farm Management, Industrial Organization, Production Economics, D2, D21, Q1, Q12,

Coordinated design of coding and modulation systems

The joint optimization of the coding and modulation systems employed in telemetry systems was investigated. Emphasis was placed on formulating inner and outer coding standards used by the Goddard Spaceflight Center. Convolutional codes were found that are nearly optimum for use with Viterbi decoding in the inner coding of concatenated coding systems. A convolutional code, the unit-memory code, was discovered and is ideal for inner system usage because of its byte-oriented structure. Simulations of sequential decoding on the deep-space channel were carried out to compare directly various convolutional codes that are proposed for use in deep-space systems

Corn and Soybean Response to Rotation Sequence and Tillage System

The response of corn (Zea mays L.) and soybean [Glycine max L. (Merr.)] to tillage system and rotation sequence has been investigated for 15 years in Wisconsin. Our objective was to compare yield and economics of conventional and no-tillage systems with different rotation sequences involving 1st-, 2nd-, 3rd-, 4th-, 5th-yr corn or soybean, alternate corn and soybean, and continuous corn or soybean. There was an interaction of corn yield with tillage system and rotation sequence. Averaged over years, tillage increased corn yield 8%, but did not affect soybean yield. Both 1st-yr corn and soybean produced the highest yields at 172 bu acre-1 and 59 bu acre·1 compared to the other six rotation sequences that averaged 148 bu acre-1 and 54 bu acre· 1, respectively Both 1st-yr corn and soybean produced the highest grower return at $80 acre· 1 and$108 acre·1, respectively Interactions for both corn and soybean grower return were found with tillage system and rotation sequence. Averaged over years, tillage increased corn grower return by $2 7 acre-1, but did not affect soybean grower return. It was concluded that 1st –year corn or soybean and alternating corn and soybean were the most profitable rotation sequences over the last 15 years in Wisconsin

A Study of Compensation

Although pages have been written in psychological text books on compensation, a survey of the literature shows an extremely meagre amount of experimental data. The present study is an attempt to formulate some of the problems of compensation into experimental form. Forty subjects were given a series of laboratory tests in which accuracy and speed were compared under normal conditions and under conditions of distraction. Thirty-one of the same subjects were given a written test of the questionnaire type which was divided into three arbitrary categories; traffic compensation (T), social compensation (S), and industry or ambition (I). The following correlations were obtained: rST + .210, rSI - .221, rTI + .309. There was no significant correlation between grade discrepancies as a measure of compensation and laboratory or written-test measures of compensation. The latter two correlated + .12 which was not as high as intercorrelations between categories of the written test. The tentative conclusion is that compensation is a more or less specific function. Further data are being obtained

Growth and Segregation of Intermenallic Phases in Zirconium Alloys

Relations between the processes of growth of intermetallic inclusions and their surface segregation in binary and ternary alloys of zirconium are presented. An increased surface concentration of iron atoms was observed, and is associated with intermetallic inclusion growth with increased annealing temperature of the deformed alloys. Modelling the asymmetric growth of these intermetallic inclusions, leading to their migration, have enabled the determination of the diffusion coefficient of iron in these intermetallics. Keywords: Zirconium alloys, Iron state, Mössbauer effec

The Effect of Cluster Size Variability on Statistical Power in Cluster-Randomized Trials

The frequency of cluster-randomized trials (CRTs) in peer-reviewed literature has increased exponentially over the past two decades. CRTs are a valuable tool for studying interventions that cannot be effectively implemented or randomized at the individual level. However, some aspects of the design and analysis of data from CRTs are more complex than those for individually randomized controlled trials. One of the key components to designing a successful CRT is calculating the proper sample size (i.e. number of clusters) needed to attain an acceptable level of statistical power. In order to do this, a researcher must make assumptions about the value of several variables, including a fixed mean cluster size. In practice, cluster size can often vary dramatically. Few studies account for the effect of cluster size variation when assessing the statistical power for a given trial. We conducted a simulation study to investigate how the statistical power of CRTs changes with variable cluster sizes. In general, we observed that increases in cluster size variability lead to a decrease in power