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L.R. Adam and M.K. Pritchard

An inexpensive system for monitoring and controlling relative humidity (RH) above 90% and for monitoring temperature was developed and tested in a storage research facility for horticultural crops. A general-purpose IBM-PC microcomputer connected to an analog/digital interface system allowed for 16 differential analog inputs and 12 digital outputs for monitoring temperature and RH in eight storage rooms. Relative humidity, measured at 2-min intervals by an inexpensive wet/dry bulb psychrometer in each room, was regulated by a cool-mist humidification system. The standard deviation of RH from set-point was ± 2.8% at 2C and ±3.1% at 10C dry bulb temperature. The software. written in BASIC, allows for additional upgrading to meet future requirements. Commercially available components were used to construct the system at a cost of about Cd$1400 (Canadian) (microcomputer and cool-mist humidification system excluded).

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A.R. Dixon, R.B. Boone, A. Gardea, L.S. Daley, and T.L. Righetti

A microcomputer-based image processing system was used to simplify the large number of visual comparisons required to identify various Corylus spp., cultivars, and clonal accessions using polyacrylamide gel electrophoresis isozyme patterns. Photographs of gels stained for peroxidase, acid phosphatase, and phenol oxidase were digitally captured and selected lanes were enhanced and scanned. The scan data were analyzed to locate bands and normalize their position to that of standards. Such data were plotted and a computer-generated isozyme pattern was displayed. Compressed image data were then stored in a database for subsequent automated isozyme pattern comparisons. Photographic records that were previously used in published reports were reevaluated with the computerized system. Species, cultivars, or clones that were characterized in visual evaluations were similarly characterized using the computer method. Computer evaluations usually identified more bands. Band positions were only rarely different and probably resulted from better normalization relative to standard bands when using the computerized procedure.

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Shahrokh Khanizadeh

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Richard H. Ozminkowski Jr., Robert H. Moll, and Randolph G. Gardner

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Jack E. Staub and Karl Braunschweig

A teaching module was developed for computer-aided instruction of mutation theory. The Hypercard-driven, Macintosh compatible module illustrates the concepts of: 1) Changes in allele frequency with mutation pressure; 2) Number of alleles maintained in populations, and; 3) The Neutrality Hypothesis. The concepts are integrated in an application by using a game format.

Mutation is the ultimate source of genetic variation. Mutation pressure results in changes in allele frequency. Concept 1 illustrates the theoretical changes in allele frequency under pressure of reversible mutation. Mutation equilibrium is depicted as P=V/u+v; where v=mutation rates of allele A and u of allele a. The Infinite-Alleles Model of mutation is illustrated in Concept 2 and specifies characteristics of new mutations by F=1/4Nu+1, where F=fixation index and N=number in population. Concept 3 demonstrates the hypothesis that polymorphisms result from selectively neutral alleles maintained in a balance between mutation and random genetic drift.

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Jack E. Staub and Karl Braunschweig

A teaching module was developed for computer-aided instruction of mutation theory. The Hypercard-driven, Macintosh compatible module illustrates the concepts of: 1) Changes in allele frequency with mutation pressure; 2) Number of alleles maintained in populations, and; 3) The Neutrality Hypothesis. The concepts are integrated in an application by using a game format.

Mutation is the ultimate source of genetic variation. Mutation pressure results in changes in allele frequency. Concept 1 illustrates the theoretical changes in allele frequency under pressure of reversible mutation. Mutation equilibrium is depicted as P=V/u+v; where v=mutation rates of allele A and u of allele a. The Infinite-Alleles Model of mutation is illustrated in Concept 2 and specifies characteristics of new mutations by F=1/4Nu+1, where F=fixation index and N=number in population. Concept 3 demonstrates the hypothesis that polymorphisms result from selectively neutral alleles maintained in a balance between mutation and random genetic drift.

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P.C. St. Amand and D.R. La Bonte

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Robert L. Wample, Guy Reisenauer, Andy Bary, and Fred Schuetze

A computerized system capable of controlling the freezing rate and collecting, storing, and analyzing data from multiple samples to determine their freezing point using low-temperature exotherm analysis is described. Details include electrical diagrams of modifications to the multiplexer/amplifier interface to provide additional signal amplification and permit control of the freezer's compressor. Computer software is described that permits variable temperature decline rates. Data analysis consists of a program in “C” that sequentially compares each data point in a low-temperature exotherm profile. Low-temperature exotherms are identified by a user-specified minimum differential between sequential data points. Examples of exotherm output and data analysis are given.