Applicability of a Differential Analyzer to Determination of Protein Fractions by the Electrophoretic Technic

Abstract

This laboratory has found it advantageous to use a differential analyzer in place of a planimeter in connection with determination of concentrations of plasma protein fractions from electrophoretic patterns. The differential analyzer is an analogue computer developed at the Massachusetts Institute of Technology under the direction of Dr. Vannevar Bush. One was recently acquired by Wayne University. Its use was made available to us and the work was carried out at Wayne University Computation Laboratory under the direction of Prof. Arvid W. Jacobson.

Although the primary purpose of the analyzer is the solution of differential equations (1) the principles upon which it operates are quite simple. All quantities involved in the calculations are represented by the rotation of shafts. The fundamental unit is the integrator which is shown in Fig. 1. The disc A turns the wheel B by friction. Hence, a slight amount of rotation, δW of wheel B will be proportional to the product of the corresponding rotation, δY of disc A and the distance U of wheel B from the center of A; i.e.,

W = k·UΔV

Thus, if u and v vary, the rotation of wheelnism of Fig. 1 is represented by the symbol marked integrator. The symbol marked input table is a function unit used to generate the function F(X) in the machine. A graph of this function is plotted on the table, and the machine moves the carriage, to which an index or bull's-eye is attached, horizontally across the input table, while the operator works the crank in such a way as to keep the bull's-eye on the curve. The speed of the horizontal motion of the bull's-eye can be varied by the operator, depending on the slope of the curve to be followed.