Mechanically refrigerated test chambers are classified as either single stage low (-40 °C) or cascade ultralow (-70 °C) temperature systems. While cascade systems are reliable and versatile, the potential for leakage between stages within a cascade heat exchanger remains. Further, the need for two compressors and increased control mechanisms can make the system more and more complex. The only m...

A T THE suggestion of a medical friend the writer decided to investigate the use of viatmin B, in connection with turf culture. This was about a year and a half ago. Extensive investigation of this particular vitamin substance was being carried on at the nearby California Institute of Technology, HO at my friend's request a visit was made to the school and a sample was obtained with which to st...

This paper explains how to select the correct statistical test for a research project, clinical trial, or other investigation. The first step is to decide in what scale of measurement your data are as this will affect your decision-nominal, ordinal, or interval. The next stage is to consider the purpose of the analysis-for example, are you comparing independent or paired groups? Several statist...