RU2462999C2 - Device for determining prescription of person's death coming - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to criminalistics and medicine, namely to forensic medicine. Device for determining prescription of person's death coming by index of vitreous body of eye viscosity depending on time of death coming includes piezoelectric converters with probes, generator of high frequency, two generators of low frequency pulses, mixer, amplifier, converter of outlet signal, unit if information presentation. Mixer is made with possibility to form on outlet signal for excitation of shift superficial waves. For this purpose its first inlet in connected with one of two generators of low frequency via generator of pulse impact, made with possibility to supply low-frequency rectangular pulses, and the second inlet is connected with outlet of generator of high-frequency sinusoidal fluctuations. Simultaneously outlets of low frequency generators are connected with commutator, whose outlet is connected with circuit of calculation permission, connected with metre inlet. First inlet of metre is connected with binary-decimal decoder, whose outlet is connected with inlet of information presentation unit, made in form of liquid crystal indicator. Second outlet of metre is connected with unit of commutation control, by means of which switchings between first and second low frequency generators are realised. Outlet of mixer is connected with first converter of five, which is placed in the centre of contact head and is a source of superficial shift waves, with four other converters, whose outlets are connected with amplifier made in form of summing amplifier, and which are installed on circumference at the same distance from the central one, being receivers of said waves. Amplifier is connected with outlet signal converter, which includes integrator, connected with inlet of Schmidt trigger, whose outlet is connected with inlet of trigger for stopping calculation.

EFFECT: application of invention will make possible to increase sensitivity, noise-resistance of similar means of viscosimetry, as well as make it possible to determine prescription of person's death coming quickly.

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Description

The invention relates to forensics and medicine, namely to forensic medicine.

The prescription of death (CSN) of a person is proposed to be determined on the basis of measuring the viscosity of the vitreous body of his intact eye. Studies conducted in [1] by us show that the vitreous body rapidly liquefies, starting from the first hours after death. After the first day from the moment of death, the process slows down, and after 30 hours the dynamics of liquefaction is barely captured. Thus, the use of the liquefaction of the vitreous body to establish CSN is advisable only in the first 30 hours after death. In this case, the dependence of the viscosity of the vitreous on the CSN (Fig. 1) is exponential (the first 8 hours the viscosity decreases from 7.9 to 4.12 units of relative viscosity (EOB), from 8 to 30 hours it decreases from 4.12 to 2.8 units) [1].

In connection with the foregoing, taking into account the fact that the proposed device actually determines the viscosity of the vitreous body of the eye, technical means for measuring viscosity are considered as analogues of the proposed device.

The following can be attributed to analogues: technical means of viscometry, which allow estimating the viscosity of liquid media in accordance with the hydrodynamic theory, and technical means based on measuring the propagation velocity of a surface acoustic wave over the surface of a tissue under investigation (ultrasonic viscometry).

Closest to the claimed solution is a device whose operating principle is based on measuring the propagation velocity of surface acoustic (shear) waves over the surface of the tissue under study [2, 3]. Unlike longitudinal acoustic waves propagating in the medium volume, surface shear waves decay at a distance equal to several wavelengths, which creates certain difficulties in studying the features of their propagation. These waves are obtained and recorded using bimorph type transducers, in which plates of piezoelectric material are used. The transducers are equipped with probes that allow for point contact with the tissue site to be examined. One of the transducers serves as a source, the second as a receiver of surface waves. The shear elasticity of biological tissues for small amplitudes of displacement of the particles of the medium is directly proportional to the square of the speed of propagation of an acoustic wave excited by a point oscillating transducer [2]:

where E is the dynamic shear modulus;

k is the coefficient of proportionality, depending on the direction of displacement of the particles of the medium;

ρ is the density of the medium;

c is the shear wave propagation velocity.

The disadvantage of the analog device is the presence of only two piezoelectric transducers, which makes it difficult to register surface shear waves due to their rapid attenuation (at a distance equal to several wavelengths), on the one hand, and the need for measurements for small displacement amplitudes of the particles of the studied medium (only in this case, the expression (1)) takes place, on the other.

A distinctive feature of the proposed device is that the contact measuring head, superimposed on the elastic surface of the eye in the protein area, contains five piezoelectric transducers with probes. One of them, located in the center, is a source of surface shear waves, and the remaining four transducers, installed around a circle at the same distance from the first, are the receivers of these waves (Fig. 2). This provides spatial and temporal summation of oscillations, which increases the sensitivity of the device, noise immunity and reliability of measurements.

In addition, the device is compact, wearable, with low current consumption and with an autonomous power source.

The technical result is a simple device that does not require complex manipulations, characterized by high sensitivity, noise immunity, and the ability to quickly determine the limitation of the onset of death when examining a corpse at the scene of an accident according to the viscosity of the vitreous body of his intact eye within up to 30 hours from the time of death. Based on the research carried out in [1], as well as in the Dagestan Republican Bureau of Forensic Medical Examination together with the Department of Biotechnical and Medical Devices and Systems of the Dagestan State Technical University to determine the vitreous viscosity of intact eyes on corpses. These studies have shown that there is a clear functional relationship between viscosity and time elapsed since death. viscosity changes in time from the moment a person dies. Moreover, the averaged changes in the viscosity of the vitreous obey the exponential law depending on the CSN up to 30 hours. The dependence of the relative viscosity ξ on the time τ elapsed after the death of a person, obtained by us in the research process, is shown in figure 1,

The structural diagram of a device for determining human DNS is shown in Fig.3.

The device operates as follows. Prior to the measurement, the corpse is laid face up; open eyelids; on the elastic surface of the intact eye 12, the contact head of the measuring transducer is superimposed into the protein region (Fig. 2: 1 - probes of the piezoelectric transducer, 2 - piezoelectric transducers, 3 - lead cable).

The contact head includes five transducers (PP) 13-17 with probes at the ends (Fig.3) for contact with the protein region of the eye, and the probe 13, located in the center, is a source of surface shear waves, and the remaining 12-17 installed circumferentially at the same distance from the first, are the receivers of these waves. This provides spatial and temporal summation of oscillations, which increases the sensitivity of the device, noise immunity and reliability of measurements.

When you press the Start button, the account resolution circuit (СРС) 11 through the trigger (Т) 7 (Fig. 3) gives the resolution of pulse counting to the counter (MF) 18 from one of the low-frequency generators (LFO) 5 or 6 (the choice of the generator the presence of two linear sections of measurements with different angles of inclination of the curve (Fig. 1, (0-A) and (AB)). Although the viscosity of the vitreous is actually measured here, the calculation is in units of the statute of death. 1) 5 to the generator (GNF-2) 6 through the switch (K) 9 is made by a signal from the output of the control unit by switching (BUK) 19 when the count reaches a predetermined number of values on the second output of the counter (MF) 18 (if the age of death exceeds 8 hours (see Fig. 1)). From the first output of counter 18, the pulses are fed to a binary decimal decoder ( DSH) 21 and to the information display unit, made in the form of a four-digit liquid crystal display (LCD) 23 for indication.

Simultaneously with the beginning of the counting, from the output of the generator (LFO-1) 5 a sequence of pulses is fed to a pulse shaper (PIV) 8, from the output of which low-frequency rectangular modulating pulses are fed to one of the inputs of the mixer (C) 10. The second input of the mixer 10 is fed high-frequency sinusoidal oscillations from a high-frequency generator (HHF) 4. From the output of the mixer 10, high-frequency pulses of a rectangular shape are fed to the input of a central piezoelectric transducer (PP) 13, which is a source of surface shear game waves. The piezoelectric transducer 13 excites shear vibrations on the surface of the protein region of the studied eyeball. Installed around the circumference at the same distance from the piezoelectric transducer 13, the piezoelectric transducers (PP) 14-17 are shear wave receivers (see FIG. 2), which convert mechanical vibrations into electrical vibrations, which then go to the inputs of the summing amplifier (SU) 20. The total electrical signal with the output of the summing amplifier (SU) 20 is fed to the input of the integrator (I) 22 and then to the Schmitt trigger (TS) 24, the output of which is generated by a pulse whose leading edge stops the counting by means of the trigger (T) 7.

Experimental studies conducted on a laboratory mock-up yielded the following results: 95% of all observations with actual deaths of up to 24 hours fell within the boundaries defined in accordance with the schedule (Fig. 1). Moreover, deviations from the actual time of death in the interval from 0 to 4 hours amounted to 22.8%; from 4 to 8 hours - 22.8%; in the range from 8 to 12 hours - 19.3%; 12-16 hours - 29.8% and from 16 to 24 hours - 5.3%.

Information sources

1. A.A. Ermilov. Forensic significance of some posthumous changes in the vitreous fluid of the eye to determine the age of death. - Krasnoyarsk, 1973, - 174 p.

2. Hakobyan B.V., Ershov Yu.A. Fundamentals of the interaction of ultrasound with biological objects: Textbook. allowance. - M.: Publishing House of MSTU. N.E.Bauman, 2005, - 224 p.

3. Fridman F.E., Gundorova R.A., Kodzov M.B. Ultrasound in ophthalmology. - M .: Medicine, 1989, - 247 p.

Claims (1)

A device for determining the age of death of a person, including piezoelectric transducers with probes, a high-frequency generator, two low-frequency pulse generators, a mixer, an amplifier, an output signal converter, an information display unit, characterized in that the mixer is configured to generate an output signal for excitation shear surface waves, for which its first input is connected to one of two low-frequency generators through a pulse shaper, performed with the possibility of supplying low-frequency rectangular pulses, and the second input is connected to the output of the high-frequency sinusoidal oscillator, while the outputs of the low-frequency generators are connected to a switch, the output of which is connected to the count resolution circuitry connected to the counter input, the first counter input is connected to a binary decimal code the output of which is connected to the input of the information display unit, made in the form of a liquid crystal indicator, the second output of the counter is connected to the unit switching by means of which switching between the first and second low-frequency generators is carried out, the mixer output is connected to the first converter of five, placed in the center of the contact head and serving as a source of surface shear waves, the receivers of which are simultaneously four other transducers installed at the same distance around the circumference from the central one, the outputs of which are connected to an amplifier made in the form of a summing amplifier connected to a converter in output signal, comprising an integrator coupled to the input of Schmitt trigger whose output is connected to the input of a trigger for stopping bills.

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