From Big Medical Encyclopedia

NOMOGRAM (grech, nomos the law + gramma record) — the expression of functional dependence between values of variables presented in the form of schedules or drawings. In N.'s medicine are applied in hygiene, physiology of work, ergonomics and other medical disciplines studying interrelation of an organism with the environment or funkts, dependences between reactions of separate systems.

The simplest type of N. is the schedule establishing dependence between two variables. There are N. for three and more interconnected variables. On N. the set area of change of variables, value is represented to-rykh it is represented by the corresponding geometrical element (a point or the line). N are widely applied in mathematics to graphic finding of result at the solution of the equations with various numerical data. N.'s example is the slide rule.

N.'s example in physiology of work are: N of temperature limits of ways of a thermolysis, N. of the thermal stress caused by work; N of intensity of various noise, and also noise levels; N of a day-night rhythm, constructed on the basis of such fiziol, variable as body temperature, the volume and composition of urine etc. At design of clothes N. of dependence of a thermal flow and thermal resistance of heat-protective packages (thickness of materials and air gaps) on ambient temperature, speed of wind, and also energy expenditure of the person are used.

N are under construction on the basis of the numerous pilot studies allowing to reveal certain mathematical dependences between these or those phenomena. In the simplest case of N. is under construction so that values of two variables are postponed in the corresponding scale of a coordinate, and the third variable forms a number of curves, values of points to-rykh calculate by the formula connecting all three variables.

the Nomogram for determination of surface area of a body of the person depending on his growth and weight.

Sometimes dependence between sizes is expressed by means of the scales applied on one or two straight lines. N. N. for determination of surface area of a body of the person depending on his growth and weight (fig.) can be an example of this kind.

Performance of calculations according to N. is followed by insignificant errors because of impossibility of exact definition of necessary compliance between elements of the nomogram. Accuracy of calculation according to N. depends also on accuracy of performance of necessary operations. At calculation according to N. it is necessary to apply a transparent ruler with longitudinal vizirny line.

The N used in medical practice display the general patterns and are acceptable for approximate, approximate calculations. The amendments considering adaptation, age, sexual and other features of an organism are necessary for final conclusions.

Bibliography: Afanasyeva R. F. Hygienic bases of design of clothes for protection against cold, M., 1977; Barton A. and Edkholm O. of People in cold, the lane with English, M., 1957; Dedenko I. I., Pus-in and I am N. K. and Ivanov V. S. Limits of portability the person of infrared radiation at local radiation, Tousle. biol, and medical, t. 2, No. 3, page 73, 1968; Singleton V. T. Introduction to ergonomics, the lane with English, M., 1974; Cher-r e r Zh. Fiziologiya of work (ergonomy), the lane with fr., M., 1973; Experimental physiology, the lane with English, under the editorship of M. A. Kamenskaya, M., 1974.

I. I. Dedenko.