BIOMETRICS

From Big Medical Encyclopedia

BIOMETRICS (grech, life + to measure bios by metreo) — set of methods and methods of mathematical processing of quantitative data in biology and medicine.

The term «biometrics» was offered by the English scientist Francis F. Galton in the book «Natural Inheritance» (1889); the beginning of its use to biological problems belongs to 1901 when the special magazine «Biometrika» was founded.

The first attempt of quantitative interpretation of variability of physical signs and behavior of the person was made by the Belgian scientific L. Quetelet in the book «Experience of Social Physics» (1835). And in the middle of 19 century already many outstanding biologists noted value of mathematics in biology. B. reached special development in 20 century in connection with progress in the field of probability theory and mathematical statistics, emergence of cybernetics. The mathematical statistics is widely used during the studying of variability of signs of a structure and functioning of a human body depending on living conditions and age. Recently not only morphological features of the person are exposed to biometric studying (see. Anthropometry ), but also signs fiziologo-biochemical. Variability of the last is characterized by right-hand asymmetry, edges often demonstrates

existence in the studied material of individuals with these or that patholologically the changed properties. Physiological, biochemical and mental indicators and their age dynamics and variations are especially important in pediatrics and gerontology. Biometric researches of specific and intraspecific variability of pathogenic organisms and viruses allow to establish distinctions between pathogenic and nonpathogenic forms. The statistical method in biology at the solution of questions of reference of separate individuals or groups to these or those systematic categories (subspecies, races, types etc.) has big perspectives. The method of discriminant functions offered by R. Fisher in 1936 was improved by A. A. Lyubishchev (1962) and applied in an anthropological research at the solution of a question of belonging of separate skulls to this or that group and some questions of medical diagnosis.

For definition of dependence of these or those biological phenomena on factors of the environment, napr, frequencies of reductions of heart of cold-bloodeds from temperature, survival of the lowest organisms at a different temperature, etc., use method of drawing the experimental data on the schedules limited to two coordinates. Through points of observations carry out curves, or at first find empirical formulas of dependence on a method of least squares (see Leastsquares a method) and already on formulas build empirical curves. In certain cases at three variables connected with each other build charts with three coordinates. Then dependence between the phenomena is expressed by surface area, but not a curve. The bigger number of explanatory variables is graphically difficult represented, but mathematically it can be investigated by the corresponding methods. Empirical dependences can be rectilinear, parabolic, indicative, logarithmic, etc. For bystry finding of constants of empirical formulas to turn reasonablly curvilinear dependences in rectilinear by change of coordinates. For this purpose there are special cliches — grids with a coordinate (half-logarithmic in which divisions of one coordinate are ruled logarithmic, double logarithmic, etc.). In pharmacology also alignment of experimental data on action of various doses of medicinal substances on these or those functions of an organism is widely applied: S-shaped communication between a dose and effect turns into rectilinear. For this purpose use a so-called method of the analysis of curves of mortality, or it is punched - the method allowing to compare objectively activity of drugs and toxicants. This method is applied in microbiology, radiobiology, toxicology, to biological standardization of substances which chemical nature is not found out yet and which cannot be standardized by quantity of these or those chemically precisely defined components.

The modern therapeutic statistics evolved from the methods of mathematical statistics developed in relation to field agronomical and zootechnical experiments. Implementation of a new therapeutic or surgical method can be recommended only after statistically reasonable tests giving high confidence in a nonrandomness of the gained effect. Testing of a new preventive or therapeutic method takes place in three stages:

1) create the scheme of testing or the plan of a research; 2) select experimental and control groups of investigated; 3) make statistical assessment of the received results.

Mathematical modeling became the following stage of mathematization of biology and medicine. However its use is still limited to certain areas of biology and medicine, hl. obr. at the solution of theoretical questions. In general physiology, and the general biophysics, in particular, it is used during the studying of physiology of the processes proceeding in a nervous system and in sense bodys. The method of the mathematical analysis consists in the following: the researcher creates a working hypothesis about communication of these or those phenomena with each other in mathematical expression — so-called mathematical model.

The results received at mathematical modeling can be checked further on experience, and in case of confirmation of conclusions the initial hypothesis becomes the scientific theory. Founders of the mathematical direction in biophysics can be considered G. Helmholtz, W. Nernst and P. P. Lazarev. The mathematical analysis is applied also in biology during the studying of dynamics of number of populations of various organisms, including and pathogenic. A founder of these researches is the English epidemiologist R. Ross who applied mathematics during the studying of a ratio of number of the human population struck with a malarial plasmodium and the number of mosquitoes — carriers of an infection.

The biometrics in cybernetics is the main quantitative method of the data collection and processing characterizing morphology and functioning of biological objects at various structural levels and also at assessment of pathological changes of an organism and development of decisions or managing teams at taking a step on normalization of serious conditions. Use B.'s means at specification of the anamnesis and during routine maintenances, and also at diagnosis of states (in systems of automatic control of devices of active intervention and artificial organs).

Fig. 1. The enlarged flowchart of the opened measuring registration information system (an explanation in the text).
Fig. 2. The enlarged flowchart of the closed registration and information and managing system (an explanation in the text).
Fig. 3. The enlarged flowchart of the opened measuring and registration system for mass routine maintenances (an explanation in the text).

Collecting and processing of necessary information are carried out by the sensors of primary information (SPI) transforming the measured size (e.g., the body temperature, arterial pressure, etc.) in an electric signal, intensifying devices, transmission lines of information and means of its processing. In addition, registrars (chernilnopishushchy or thermal recorders, magnetic registrars, etc.) — the P2 block (fig. 1 — 3) and means of display of information (oscilloscopes, digital cells, etc.) — the block Otbr have biometric systems, as a rule, (fig. 1 — 3). At measurement of electrophysiologic parameters the role of DPI is carried out by the electrodes withdrawing biopotentials from a certain site of an organism.

On structure biometric systems divide on opened (measuring registration information systems) and closed (registration and information and managing systems). In figures 1 and 2 the enlarged block diagrams of both types of systems are submitted.

Depending on frequency characteristics biological processes divide on fast changing (PIP) — the frequency of signals within 1 — 100 Hz and slow changing (MIP) — frequency less than 1 Hz. MIP have numerical expression and can be presented or the size of voltage, or after strengthening (in the MOUSTACHE block) and transformations (in the block of Prb) in digital display or in the corresponding code. The autoanalyzer of states (AS) intended for complex information processing about MIP and PIP and issues of the generalized decision on a condition of a controlled organism can be entered into biometric system. Treat the main indicators characterizing MIP: heart rate, the central and peripheric pulse, a respiration rate, volume of a breath and an exhalation, minute volume of breath, speed of flows of air on a breath and an exhalation, temperature (body surfaces, rectal, esophageal), arterial and venous pressure (maximum, minimum and average), percentage of oxygen and carbonic acid in blood, partial pressure of hydrogen, oxygen, carbonic acid, the maintenance of ions of sodium and potassium, rate of volume flow of a blood-groove, etc.

A pip are registered in the form of the curve tension and direct numerical expression have no. In this regard for use of information about the PIP in automated opened as well as in the closed, managing diagnostic complexes pretreatment of signals for the purpose of identification of informative signs is necessary. This operation and coding of signs are made in the special computer — the block of allocation of informative signs (BAIS). The useful information revealed thus from a signal the PIP comes to the autoanalyzer of states.

To most eurysynusic registered the PIP belong: electric activity of heart (electrocardiogram), electric activity of a brain (electroencephalogram), electric activity of motive muscles (electromyogram), mechanical activity of heart (a ballistokardiogramma, the mechanocardiogram, the seismocardiogram, a valvulokardiogramma, etc.), the intracavitary acoustic field of heart (phonocardiogram), change of electric characteristics under the influence of dynamics of blood circulation (reogramm), kozhnogalvanichesky reaction (KGR), change of a krovenapolneniye of vessels (plethysmogram), a physical activity of eyes (okulogramm), change of arterial and venous pressure, rate of volume flow of a blood-groove, etc.

Depending on purpose of measuring registration and information complexes the volume of information with MIP and PIP can change in rather wide limits.

In the systems of continuous control which are especially servicing resuscitation and surgical complexes as well as in physiological laboratories, so-called acute methods of measurements at which DPI place on various body parts with disturbance of an integument are allowed. At routine maintenances, and also at continuous control of activity of healthy people (e.g., the operators servicing control systems) usually acute methods of measurement are not applied.

Loop systems essentially differ from opened by existence of the managing part which is turning on the control unit of devices of active intervention (CUDAI), the devices of active intervention (DAI) and the control system behind operation of devices of active intervention (Counter. Surfactant).

BUPAV represents the computing system realizing the tough or adaptive program of management of the surfactants modes. At the same time the control algorithm provides use of information from AAS and Counter. Surfactant for the choice and optimization of a duty surfactant.

According to the carried-out surfactants functions divide into the following groups: 1) artificial organs (the device «artificial heart lungs», the cardiopulmonary bypass — AIK, artificial kidneys, medical ventilators, etc.); 2) stimulators (electrocardiostimulators, pharmacological stimulators, etc.); 3) control systems of parameters of the environment (temperature, humidity, illumination, the maintenance of gas components in air, sources of electromagnetic and radiation fields, etc.).

The main requirement providing sufficient reliability of information obtained by means of biometric systems is the minimum of hindrances. From this point of view microminiature sensors and methods of wireless are perspective biotelemetry (see).

One of kinds of the opened measuring and registration systems are the automated systems (fig. 3). These systems are intended for systematic mass routine maintenance. They can also play a role of a subsystem in automated control systems for the large industrial enterprises.

In these systems the measured parameters of an organism by means of DPI blocks, Prb. and BVIP are entered into the block of comparison (BC). Also the data characterizing a normality inspected, stored in the corresponding block of random access memory (BRAM) are entered into it. In case of an aberration at least of one of the measured parameters of the block of comparison the alarm signal arrives. Results of inspections can automatically be entered into the block of a long-term memory of system (BJP) representing the automated archive, from to-rogo the relevant statistical information can be in case of need taken.

In recent years at microscopic examinations the method of the optiko-structural machine analysis offered by K. M. Bogdanov found application (see the Morphometry medical). The method is based on a statistical analysis of a skanogramma (the signal received at a consecutive fotometrirovaniye of a sample) and allows to receive quantitative characteristics of distribution of structural components of cells and fabrics it is normal also of pathology, to calculate orderliness and information entropy of structure. The automated microscope analyzer Protva is developed for implementation of a method.

See also Mathematical methods (in medicine).


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V. A. Alpatov, V. M. Akhutin.

Яндекс.Метрика