Passive broadband acoustic thermometry

The 1D internal (core) temperature profiles for the model object (plasticine) and the human hand are reconstructed using the passive acoustothermometric broadband probing data. Thermal acoustic radiation is detected by a broadband (0.8–3.5 MHz) acoustic radiometer. The temperature distribution is reconstructed using a priori information corresponding to the experimental conditions. The temperature distribution for the heated model object is assumed to be monotonic. For the hand, we assume that the temperature distribution satisfies the heat-conduction equation taking into account the blood flow. The average error of reconstruction determined for plasticine from the results of independent temperature measurements is 0.6 K for a measuring time of 25 s. The reconstructed value of the core temperature of the hand (36°C) generally corresponds to physiological data. The obtained results make it possible to use passive broadband acoustic probing for measuring the core temperatures in medical procedures associated with heating of human organism tissues.     

ON A NEW CLASS OF ANALYTIC FUNCTION DERIVED BY A FRACTIONAL DIFFERENTIAL OPERATOR

Making use of the fractional differential operator, we impose and study a new class of analytic functions in the unit disk （type fractional differential equation）. The main object of this paper is to investigate inclusion relations, coefficient bound for this class. Moreover, we discuss some geometric properties of the fractional differential operator.     

Acoustic thermometric data on blood flow and thermal output in forearm under physical pressure

The influence of blood flow and thermal output on temperature changes in the human forearm under physical pressure is studied by acoustic thermometry. Compression of the shoulder with a tourniquet decreases blood flow, which make it possible to evaluate the thermal output characteristics only. In calculating the depth temperature of the forearm, the thermal conductivity equation was used and blood flow and additional thermal output sources were taken into account. According to the calculations in which the experimental data were used, the peak depth temperature of the forearm at rest is 36°C. Due to thermal output alone (without blood flow), physical pressure increases this temperature to 37°C, and when both factors are considered, the temperature rises to 38°C. The experiments in question have allowed us to test acoustic thermographic method on subjects, which is an important step in adopting acoustic thermography in clinical practice.     

Correlation reception of thermal acoustic radiation

Correlated signals of thermal acoustic radiation from heated sources extending in the transverse direction (a pair of narrow plasticine plates and a wide plasticine strip) are measured. The measurements are performed by multiplying together the signals that are shifted in time with respect to each other and detected by two piezoelectric transducers. The values of the correlated signals of thermal acoustic radiation are determined by the spatial variation of temperature in the medium under study.     

A combined application of acoustothermography and IR imaging for the temperature control in the model biological object heating procedure

An experiment that models the heating of a biological object is carried out. The model object was a beef liver. The in-depth temperature in the liver was measured in the course of both heating and cooling with the use of a chain of three acoustothermometers. Simultaneously, thermal electromagnetic radiation in the IR range was detected to control the surface temperature of the object. The results of the acoustothermometric measurements and the IR imaging correlate well with the heating-cooling dynamics. A combined application of acoustothermometers and IR imaging enhances the reliability of the temperature measurements.     

Determination of the dynamics of temperature variation in a model object by acoustic thermography

An experiment on monitoring the dynamics of internal temperature variation in a model object by the acoustic thermography method is carried out. The measurements were performed in a cell filled with an aqueous solution of glycerol, into which a plasticine object was placed. Thermal acoustic radiation of the object was measured in the course of its heating and cooling. Two bars of acoustic thermometers positioned on two sides of the object were used for this purpose. The results of measurements allowed the reconstruction of the dynamics of the varying two-dimensional distribution of in-depth temperature. The position of the heated region, its temperature, and its characteristic size are estimated. In addition, an estimate is obtained for the absorption coefficient.