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The aim of the investigation was to reveal changes in the neurons of the cerebral cortex depending on the dose of γ-irradiation, the dose rate of exposure, the mode of exposure (acute and chronic) and to establish the priority of each of the influencing factors (γ-irradiation, recovery time and their joint impact) in the end result.Material and methods. The experiment, in compliance with the rules of bioethics, was carried out on 300 adult white rats that were exposed to acute and chronic γ-irradiation in total doses from 10 to 100 cGy with a dose rate of 50 to 660 cGy/h. The sensory and motor areas of the cerebral cortex were studied throughout life after exposure to radiation using traditional neuromorphological, histochemical, and statistical methods, followed by mathematical modeling of the obtained evaluation criteria.Results. Despite the peculiarities of the regimes of radiation exposure, all of them did not cause statistically significant changes in functionally different areas of the cerebral cortex. Throughout the entire recovery period, both in control and experimental animals, phase stochastic changes were observed in various neuromorphological indicators of the state of nerve cells, which, as a rule, had a borderline character, and the level of their significance fluctuated in relation to the control within insignificant limits. At the same time, the change in some neuromorphological parameters was more influenced by the dose or dose rate of γ-irradiation, while others were influenced by the recovery time. With the combined effect of the radiation factor and the duration of the recovery period, most of the indicators corresponded to the age control.Conclusion. Statistically significant changes in the state of neurons in both sensory and motor areas of the cerebral cortex under the considered modes of γ-irradiation in total doses up to 100 cGy were not revealed.

Radiogenomics is a novel and promising field connecting a variety of imaging possibilities with various genomic events. Advances in genomics provided by the Cancer Genome Atlas and Human Genome projects made it possible to integrate this information with imaging phenotypes of malignant brain tumors for a more detailed understanding of their biology. Radiomics, in turn, lies at the intersection of radiology, computer science and mathematical statistics. Unlike radiogenomics, it does not focus on the specific relationship between the radiophenotype and tumor genotype, but rather identifies the analysis methodology. With its help, quantitative features are extracted from medical images, establishing patient’s genotype-phenotype correlation. This contributes to the risk stratification and patient management. The article discusses some topical aspects of radiomics and radiogenomics of glioblastomas and their application in neurooncology.Previously, several groups of researchers showed the relationship between visualization features of glioblastomas and the prognosis of the course of the disease.One of the modern problems of radiomics is the search for imaging features that can serve as key prognostic markers for risk stratification of patients with glioblastomas using machine learning tools.Thus, the prospects for the development of radiomics and radiogenomics methods include predicting patient survival, differential diagnosis of glioblastomas, determining the degree of malignancy, identifying mutations and amplifications, detecting tumor progression, pseudoprogression, etc.

According to 2019 statistics records, traumatic brain injuries (TBI) are the most common type of injuries and one of the main causes for disability in Russia. Every year 200 people per 10,000 subjects around the world suffer from serious brain injuries. Severe TBI can result in long-term disability. Posttraumatic epilepsy (PTE) is one of the most dramatic consequences of TBI with an estimated incidence rate ranging from 2% to 50% based on severity of injury. Conducting studies on PTE poses numerous challenges because epilepsy never develops in many patients with TBI or it may occur more than 10 years after TBI.In this review, which includes data from studies conducted by Russian researchers, including us, and foreign colleagues over the last few years (mainly 2017–2022), we analyzed and generalized currently known risk factors, clinical and diagnostic features of PTE in order to increase the awareness about modern methods of laboratory and instrumental diagnostics related to this disease (including electroencephalography and routine/special neuroimaging techniques that allow to identify PTE biomarkers). We also aimed to promote development of preventive strategies for patient management. It has been proved that no clear algorithms for PTE diagnostics and treatment are currently available, which often leads to insufficient patient care.

Respiratory system pathology is the most common clinical disorder associated with COVID-19. However, there are also lesions of the immune, cardiovascular, genitourinary, endocrine systems, and digestive tract. In addition, there are numerous reports on infection-related neurological manifestations, which can be divided into 3 groups: central nervous system manifestations (headache and dizziness, stroke, encephalopathy, encephalitis, acute myelitis), lesions of the peripheral nervous system (anosmia, Guillain–Barre syndrome), secondary lesions in the skeletal muscles. Brain damage that occurs during novel coronavirus infection and determines some of the above-mentioned manifestations often account for the development of structural epilepsies. Only a few scarce review articles on neuroimaging features in patients with COVID-19 have been found in Russian research publications.The objective of the review was to collect, analyze and summarize the results of brain magnetic resonance imaging (MRI), currently accumulated worldwide in patients with COVID-19. We present the most common diagnoses based on brain MRI in patients with COVID-19 established by foreign researchers from March 2020 to March 2021, as well as initial attempts to interpret the pathophysiological mechanisms of the changes observed in the brain substance.

This paper presents results of calculation studies of the viability of coated particles in the conditions of the reactor core on fast neutrons with sodium cooling, justifying the development of the concept of the reactor BN with microspherical fuel. Traditional rod fuel assemblies with pellet MOX fuel in the core of a fast sodium reactor are directly replaced by fuel assemblies with micro-spherical mixed (U,Pu)C-fuel. Due to the fact that the micro-spherical (U, Pu)C fuel has a developed heat removal surface and that the design solution for the fuel assembly with coated particles is horizontal cooling of the microspherical fuel, the core has additional possibilities of increasing inherent (passive) safety and improve the competitiveness of BN type of reactors. It is obvious from obtained results that the microspherical (U, Pu)C fuel is limited with the maximal burn-up depth of ∼11% of heavy atoms in conditions of the sodium-cooled fast reactor core at the conservative approach; it gives the possibility of reaching stated thermal-hydraulic and neutron-physical characteristics. Such a tolerant fuel makes it less likely that fission products will enter the primary circuit in case of accidents with loss of coolant and the introduction of positive reactivity, since the coating of microspherical fuel withstands higher temperatures than the steel shell of traditional rod-type fuel elements.

The possibility of creating an experimental setup in building No.3 of the IHEPNP NNC KIPT (LUE-300 complex) on the basis of the existing LUE-60 electron accelerator and the existing experimental infrastructure is being discussed. It is planned to raise the energy of the electron beam to 100MeV and create two beam lines: one is for reaserches with intense beams of electrons and photons, including linearly polarized ones, and the other – for investigations with the low intensive beams of electrons and positrons. Implementation of the project will open opportunities for a wide range of research programs in the field of interaction of the radiation with amorphous and crystalline matter, nuclear physics and astrophysics, as well as in the applied research.

A technology of bone tissue cultivation on a thin scaffold in a rotational bioreactor is developed. An optimal regime of cell material cultivation is determined for testing the method, and an optical method for diagnostics of the bone growth dynamics during its cultivation is found. Numerical simulations of the fluid flow in the bioreactor make it possible to significantly simplify the medical experiment and to choose the optimal values of the rotation frequencies and shear stresses acting on the cell material placed on the scaffold. The optical diagnostics of the scaffold samples in the course of dynamic cultivation in the bioreactor is performed by the method of laser-induced fluorescence. An algorithm based on the principal component analysis is applied to analyze the spectral data; as a result, the spectra of excitation and fluorescent emission of the basic fluorescent substances in the sample (tyrosine and tryptophan amino acids, structural protein (collagen), and fluorescent structures of polycaprolactone) are calculated. It is found that the contribution of the component corresponding to collagen in the samples increases in the process of dynamic cultivation, which testifies to effective formation of the extracellular matrix of the bone.

The developed mathematical model was applied for study of fluid dynamics in a rotational bioreactor for bone tissue engineering by in vitro technology. The research goal is finding an optimal mode for rotation ensuring proper cyclic loading from fluid upon the cell-seeded biomaterial. The basis for developing a mathematical model of a bioreactor was a design of rotational type biological reactor used in medical research; the liquid flow is generated through viscosity mechanism due to surface rotation. Mathematical description of flow in a reactor cavity was performed with Navier—Stokes equations. It was assumed that flow regime in the boundary layer is laminar. Numerical algorithm was accomplished using a fluid flow solver “Fluent” in the code package ANSYS-12. Four variants of generating the rotational motion in the reactor cavity were considered. A series of parametric computations was performed for the rotation frequency f in the range 0.05 ≤ f ≤ 0.25 Hz. The paper offers visualization of velocity fields in the vertical plane. The distributions for shear stress and pressure in the working zone of reactor were calculated and analyzed. Simulations demonstrated that a method of fluid rotation by driving the outer cylinder with an offset axis is the best for arranging a cyclic pressure and cyclic shear stress on the biological material.

The results of the study of the influence of Cu on the Shubnikov–de Haas effect and the electrical properties of p-Sb2 –xCuxTe3 single crystals (0 ≤ x ≤ 0.1) are presented. In the framework of the parabolic model of the energy spectrum, the hole concentrations and the Fermi energy in Sb2 –xCuxTe3 are calculated based on the oscillation frequencies of the magnetoresistance. It is shown that doping by Cu has an acceptor effect and significantly increases the frequencies of Shubnikov–de Haas oscillations. A plateau is observed in the dependences of the Hall resistance on magnetic field. The dependences of the resistance on temperature obey the power law with the exponent m = 1.2, which is characteristic of scattering on phonons with the contribution of scattering on ionized impurities. Unlike other impurities, the exponent remains almost unchanged when doped by Cu to the maximum concentrations studied.

Bi2Te3/graphite nanocomposite samples were prepared by mixing different weight percentage of graphite (x=0.0, 0.5 and 1.0) with Bi2Te3 and then subsequently ball milled. XRD results indicate the solid state insolubility of graphite phases in Bi2Te3 as no shift was observed in the peaks corresponding to Bi2Te3 in the composite samples. We investigated Seebeck coefficient S, conductivity σ, thermal conductivity κ, and, hence, the thermoelectrical figure of merit ZT in the temperature interval 80 K

The technology using for the replacement of damaged tissues the own cells of the patient, which are placed in a three-dimensional frame - scaffold, is promising for solving the problem of the bone tissue regeneration. A new biological reactor of the rotational type, in which the scaffold tissue rotates in a medium for cultivating the cells, was designed for the development of this technique. A numerical algorithm based on the ANSYS program was developed, which enables one to estimate in a new bioreactor the level of the mechanical load on the cells, which affects their pro-perties. The algorithm enables the computation of the values of the shear stress and static pressure acting on the scaf-fold surface. The computations have shown that the necessary shear stress is reached in the proposed rotational biore-actor on the outer side of the inner cylinder (0.002−0.1 Pa) in the range of rotation frequencies 0.083 < f < 0.233 Hz. At the same time, computational results have revealed the presence of an inhomogeneity in the mechanical action distribution along the scaffold tissue, which is due to the appearance of two Taylor vortices with opposite rotation directions in the gap between the cylinders. The experiments on the flow field visualization inside the rotational bio-logical reactor have shown a qualitative agreement of the flow character with computational results. The proposed numerical algorithm may simulate with sufficient accuracy the fluid flow in a real system. The obtained dependencies can be used in practice for creating an optimal microenvironment of the cells cultivated in the biological reactor.

Antimony-telluride-based nanocomposite samples containing different weight fractions of graphite (Sb2Te3 + x% graphite, where x = 0.0, 0.5, 1.0, and 2.5%) are synthesized and studied. The samples are produced by a solid-state reaction with the use of a ball mill. X-ray diffraction measurements show that the Sb2Te3 phase is present in the nanocomposites. All of the diffraction peaks are identified as corresponding to the rhombohedral structure of symmetry $$R\bar {3}m$$ . No additional peaks related to graphite are observed because of its low content. Moreover, the X-ray data show the insolubility of graphite in Sb2Te3: the peaks related to Sb2Te3 remain unchanged upon the addition of graphite. The thermal conductivity, thermoelectric power, and resistivity of the samples are studied in the temperature range 80 K ≤ T ≤ 320 K. The thermal conductivity k of the nanocomposite decreases several times compared to the thermal conductivity of single-crystal Sb2Te3 and reaches k ≈ 0.95 W m–1 K–1 at x = 0.5%. The parameter k unsteadily depends on the content of graphite. The thermoelectric power of the nanocomposites with graphite at x = 1.0% is higher compared to that of nanostructured Sb2Te3.

The inheritance of epilepsy is an important problem of current neuroscience. The present report reviews the factors that impact the development of a specific disease in children born to parents with epilepsy. Due to the increasing number of patients with autism spectrum disorders it is important to continue the research into the possible relations between these diseases in children.

The role of epilepsy in developing autism spectrum disorders (ASD) is not well understood. According to some reports, epilepsy of early childhood is often found in patients with autism of early childhood. In such children, epilepsy can progress at later periods, while the presence of both disorders in one child has a specific clinical pattern and requires specific treatment. The question whether suppression of epileptic discharges on the EEG could lead to cognitive improvement in children with ASD remains open. Likewise, the etiology of autism and its possible links to epilepsy and other pediatric disorders need more research. Here we present an overview of recent clinical studies on the proposed connection between epilepsy and ASD.

Excitation–emission matrices of laser-induced fluorescence of lens capsule epithelium, the lens nucleus, and the lens capsule are investigated. A solid-state laser in combination with an optical parametric generator tunable in the range from 210 to 350 nm was used for excitation of fluorescence. The spectra of fluorescence of all three types of tissues exhibit typical features that are specific to them and drastically differ from one another. This effect can be used for intrasurgical control of presence of residual lens capsule epithelium cells in the capsular bag after surgical treatment of a cataract.

Excitation-emission matrices of various plastic package samples were studied. A tuneable 210-310 nm laser was used as an excitation source. The samples of polyethylene terephthalate, polypropylene, and high-density polyethylene of various colour and transparency showed multipeak wideband fluorescence spectra dependent on the excitation wavelength. Principal component analysis demonstrated that the excitation-emission matrices of most samples are well described by two principal components, individual for their types and colorant additives. Despite complex structure of the excitation-emission matrices of different types of the plastic, appropriate linear combinations of the principal components allowed finding a characteristic component for each of them.

The comparison of thermal imaging and thermosensitive fluorescent coating methods was performed for the investigation of heat transfer coefficient distribution during the impact of supersonic axisymmetric gas micro-jet on the heated plate. The nozzle diameter was 300 µm, the range of jet pressure ratios was n = 1−4. The heated surface was made of the polyether ether ketone. The results of thermal imaging measurements show high discrepancy with numerical simulation data due to the relatively high transparency of the used plastic for infrared radiation. As a result, the measured temperature was averaged over layer too thick for microscale. The fluorescent coating based on rhodamine B allowed us to measure temperature distributions over the surface of the heated plate in thin (2-3 µm) layer, using much simpler technical means with a higher spatial resolution than in the case of the existing thermal imaging system. The measured data shows good agreement with numerical simulation results.

Identification of the mechanical properties of the vascular tissue plays an important role in modern tasks of preoperative modeling of cerebral aneurysms. The aim of the study was to determine whether differences in the structure of healthy, unruptured and ruptured aneurism tissues can be demonstrated by laser-induced fluorescence spectroscopy. Tunable laser (210-290 nm) induced fluorescence exhibit contributions of at last four components, which were identified using narrow peak modification of principal component analysis. The pathology development shows a tendency to relative component contributions redistribution. The ultraviolet laser-induced fluorescence spectroscopy of cerebral vessel surfaces may be useful for identifying its medical condition.Identification of the mechanical properties of the vascular tissue plays an important role in modern tasks of preoperative modeling of cerebral aneurysms. The aim of the study was to determine whether differences in the structure of healthy, unruptured and ruptured aneurism tissues can be demonstrated by laser-induced fluorescence spectroscopy. Tunable laser (210-290 nm) induced fluorescence exhibit contributions of at last four components, which were identified using narrow peak modification of principal component analysis. The pathology development shows a tendency to relative component contributions redistribution. The ultraviolet laser-induced fluorescence spectroscopy of cerebral vessel surfaces may be useful for identifying its medical condition.

A simple two-component model is worked out to investigate pulsed laser-induced fluorescence in complex organic samples, like biological tissues, optically thick at the excitation wavelength. Expression for emitted fluorescence signal is obtained. Saturation process is shown to be determined not only by fluorophores excited by the laser, but non-fluorescent chromophores with overlapping absorption band as well. For homogeneous samples the forms of saturation curves are determined by fluorophore’s features. Experimental saturation curves of bulk paper and mice tissues ultraviolet pulsed laser-induced fluorescence are discussed considering this model. For the ns and shorter laser pulse durations with wavelength in 200–300 nm region, pulse energy density should be less than 200 μJ/cm2 for correct quantitative comparison of fluorescence spectra of biological tissues with primarily tryptophan fluorescence.

Laser-induced fluorescence (LIF) spectra of biological tissues spectra have continuous nature and can be statistically analyzed using principal components (PC) method. The disadvantage of this method is that PCs are abstract functions, alternating, giving both positive and negative contribution to the spectrum that it is impossible for the real fluorophores. In present paper the PC analysis was adapted to spectroscopy tasks by composing positive linear combinations of PCs corresponding to the peaks of the smallest width with the largest ratio of the spectral maximum to its integral across the measured wavelength range. This method was applied for the analysis of previously obtained LIF spectra of the intact teeth and teeth with caries, and spectra of aortal graft before and after decellularization. The representation of the principal components in the form of peaks with the smallest possible width allowed us to identify the number fluorophores contributing the spectra, their approximate spectra, to perform a statistical analysis of the data and its interpretation.

We have experimentally studied subsonic submerged air jets emitted from flat mini and micro nozzles with characteristic dimensions from 22 to 600 μm in a range of Reynolds numbers 70–2600. The point of laminar-turbulent transition (jet penetration range) was determined using the flow visualization technique. It is established that the penetration range of micro jets can reach 100–300 nozzle calibers. The Reynolds number for the transition to turbulence in flat mini and micro jets reaches high values (1000–2600), which are two to three orders of magnitude greater than the Reynolds numbers for the loss of stability (3–10). Available experimental data are summarized and generalized based on the Reynolds number determined for the jet penetration range.

The article reports on results of estimating the Pitot tube diameter effect on the streamwise and lateral pressure distributions in plane supersonic air microjets. The study is aimed at obtaining reliable information on the microjet structure. The nozzles with the size of 22.3 × 2593 μm and 83.3 × 3823 μm are used in experiments. The supersonic flow from that nozzles is investigated by glass Pitot tubes in inner/outer diameters of 24/70 and 16/42 μm. Additional measurements are performed by a Pitot microtube 8 μm in outer diameter and ≈0.1 μm wall thickness. The value ranges for accuracy determination of supersonic jets main characteristics (shock cell sizes and supersonic core length) have been found.

In the present article, the heat transfer coefficient was determined experimentally when a subsonic jet flows onto a plate. The jet escaped from axisymmetric nozzles with a diameter of d = 290, 540, and 980 μm. The experiments were carried out at the speeds of V = 5, 20, 40, 60, 80 and 100 m/s in the Reynolds numbers range of 100 – 7000. The Nusselt number distribution was obtained for different distances between the nozzle and cooled surface.

Thermoelectric properties of nanostructured Sb2Te3/graphite composites are investigated both experimentally and theoretically and the contribution of graphite to heat transport mechanism is addressed. XRD results indicate the solid state insolubility of the graphite phase in Sb2Te3 as no shift is observed in the diffraction peaks corresponding to Sb2Te3 in the composite samples. Raman spectroscopic analysis confirms the presence of graphite in the nanostructured composite samples. Temperature dependence of carrier concentration nH, thermal conductivity κ, Seebeck coefficient S, resistivity ρ, and, hence, the thermoelectric figure of merit ZT is reported. Graphite incorporation leads to around 40% decrease of κ, essentially due to the decrease of lattice thermal conductivity, κL. A low κL value of 0.8 Wm−1 K−1 is reported, which mostly arises due to enhanced phonon scattering at the heterointerfaces created by the addition of graphite. S increases in Sb2Te3/graphite nanocomposites. Calculation reveals that reported large S value is related with the low hole concentration. Theoretical simulation in the frame of Boltzmann equation approach shows satisfactory agreement of nH, S, and ρ with experimental data, and based on the modification of the density of states and its derivative near Fermi energy with graphite addition, a plausible explanation is provided.

Development of cell-mediated scaffold technologies for the treatment of critical bone defects is very important for the purpose of reparative bone regeneration. Today the properties of the bioreactor for cell-seeded scaffold cultivation are the subject of intensive research. We used the mathematical modeling of rotational reactor and construct computational algorithm with the help of ANSYS software package to develop this new procedure. The solution obtained with the help of the constructed computational algorithm is in good agreement with the analytical solution of Couette for the task of two coaxial cylinders. The series of flow computations for different rotation frequencies (1, 0.75, 0.5, 0.33, 1.125 Hz) was performed for the laminar flow regime approximation with the help of computational algorithm. It was found that Taylor vortices appear in the annular gap between the cylinders in a simulated bioreactor. It was obtained that shear stress in the range of interest (0.002–0.1 Pa) arise on outer surfac...

The main approach to tissue engineering involves the use of scaffolds seeded with cells, followed by culturing in a bioreactor. However, the effective use of a bioreactor requires adaptation of the scaffold at the stage of its design. In our opinion, this means assessment of the perfusion properties of the scaffold. Transverse and longitudinal perfusion under hydrostatic pressure of 5, 10, and 15 mmHg, as well as the significance of electrospinning parameters for fabrication of a scaffold sheet and the composition of composite material—11% w/v polycaprolactone with gelatinization of 0.5%, 2%, and 4%, were demonstrated.

Application of scaffold technology for the problem of bone tissue regeneration has great prospects in modern medicine. The influence of fluid shear stress on stem cells cultivation and its differentiation into osteoblasts is the subject of intensive research. Mathematical modeling of fluid flow in bioreactor allowed us to determine the structure of flow and estimate the level of mechanical stress on cells. The series of computations for different rotation frequencies (0.083, 0.124, 0.167, 0.2 and 0.233 Hz) was performed for the laminar flow regime approximation. It was shown that the Taylor vortices in the gap between the cylinders qualitatively change the distribution of static pressure and shear stress in the region of vortices connection. It was shown that an increase in the rotation frequency leads to an increase of the unevenness in distribution of the above mentioned functions. The obtained shear stress and static pressure dependence on the rotational frequency make it possible to choose the operating mode of the reactor depending on the provided requirements. It was shown that in the range of rotation frequencies chosen in this work (0.083 < f < 0.233 Hz), the shear stress does not exceed the known literature data (0.002 - 0.1 Pa).

Based on systematic analysis of published data and our own data, there has been worked out and introduced a concept of neurophysiological processes that developed during fatigue, over-fatigue of experts in their professional activities. The concept serves as an objective base for dynamic assessment and prediction of the experts’ functional status and health. It has been shown and proved that transition from fatigue to over-fatigue reduced protective inhibition, the effect of "disinhibition" developed, and as a consequence, speed and mobility of nervous processes increased. Volatility and differentiation inhibition increased. With further intensification of over-fatigue, the earlier formed neurophysiological changes were strengthened. Later they were joined by an equalizing phase, and then by a paradoxical phase as initial manifestations of protective inhibition. Asthenic-neurotic states were clinically diagnosed.

Using the field-ion and field-electron microscopy techniques, it is demonstrated that the efficiency of formation of field-induced-emission sources with developed (multipoint) surfaces can be increased due to the phenomenon of evaporation in a strong electric field in the presence of an active gas. The proposed emitter formation process is self-consistent and terminates upon attaining equality of local field factors over the vertices of point emitters irrespective of their initial distribution with respect to the radius of curvature and the local factor of mutual screening.

We study experimentally stimulated Brilluoin scattering (SBS) of vortex laser beams, namely, the LG11 and LG01 Laguerre -Gaussian modes. The wave front transformation is experimentally demonstrated in the case of SBS of the LG11 laser mode, directly focused into the SBS cell, when the fundamental Gaussian mode LG00 rather than the conjugate mode is selected from the Stokes beam. It is shown that optical vortices become phase conjugate by destroying the laser mode structure in the SBS cell. Phase conjugation (PC) of the LG01 and LG11 modes is obtained in the SBS mirror using a regular aberrator (microlens raster) in the system of laser beam focusing into the SBS cell.

Minimally invasive probe and optical biopsy system based on optical spectra recording and analysis seem to be a promising tool for early diagnostics of breast cancer. Light scattering and absorption spectra are generated continuously as far as the needle-like probe with one emitting and several collecting optical fibers penetrates through the tissues toward to the suspicious area. That allows analyzing not only the state of local site, but also the structure of tissues along the needle trace. The suggested method has the advantages of automated on-line diagnosing and minimal tissue destruction and in parallel with the conventional diagnostic procedures provides the ground for decision-making. 165 medical trials were completed in Nizhny Novgorod Regional Oncology Centre, Russia. Independent diagnoses were the results of fine biopsy and histology. Application of wavelet expansion and clasterization techniques for spectra analysis revealed several main spectral types for malignant and benign tumors. Automatic classification algorithm demonstrated specificity ∼90% and sensitivity ∼91%. Large amount of information, fuzziness in criteria and data noisiness make neural networks to be an attractive analytic tool. The model based on three-layer perceptron was tested over the sample of 29 ‘cancer’ and 29 ‘non-cancer’ cases and demonstrated total separation.

The possibility of pump diagnostics on the basis of its duration of deceleration is considered. A test bench with an inertial drive is developed for positive-displacement pumps, along with corresponding methods of analysis.

We report the three-dimensional simulation results of phase conjugation upon nonstationary stimulated Brillouin scattering of a focused laser beam. It is shown that in the case of deep focusing of laser radiation in the SBS cell, the phase conjugation quality decreases with increasing laser power and reflection coefficient, in agreement with experimental results. In calculations, the process of Stokes radiation generation is studied in detail, the reasons for a decrease in the phase conjugation quality are explained, and a means of its improvement is proposed.

One of the main unsolved problems in traumatology and orthopedics is reconstruction of critical-sized segmental bone defects. We believe that implementation of noninvasive monitoring of the bioengineering stages for cell-mediated bone scaffold by laser-induced fluorescence (LIF) can become a positive aspect in mastering this technique. An electrospun scaffold model (parameters: 10 wt. % polycaprolactone; 5% wt type A gelatin; mean fiber diameter 877.1 ± 169.1, and contact angle 45.3°) seeded with BHK IR cell culture (182 ± 38 cells/mm2) was used to show the principal possibility of differentiating between the scaffold seeded and unseeded with cells. First of all, the fluorescence spectra of the cell-seeded scaffold contain a peak at 305 nm for the excitation range of 230–290 nm, which can be used to differentiate between the samples. An increase in fluorescence intensity of the cell-seeded scaffold in the range of 400– 580 nm upon excitation at 230–340 nm is also noticeable. The wavelength of 250 nm is ch...

The present widespread conceptual model of the neurophysiological picture of human fatigue, chronic fatigue, and overfatigue is limited to the picture of hypoexcitability and development of inhibitory processes in the CNS. The results of this study show that, when fatigue deepens and is followed by chronic fatigue and overfatigue, the inhibitory processes that developed earlier weaken. The speed of nervous processes and their lability increase in this period, exceeding the initial “normal” baseline values; the differential inhibition strengthens. Both main nervous processes weaken; the excitatory process begins to relatively predominate. The equalization and paradoxical phases manifest themselves in the CNS functioning. As fatigue deepens and overfatigue develops, excitability of nervous structures continues decreasing. Interhemispheric asymmetry increases.

Axially oriented crystals, penetrated by high-energy electrons, are powerful photon sources and, hence, intense positron sources. Such kinds of positron sources have been studied experimentally at CERN, with the tertiary electron beam of the SPS having an energy of 6 and 10 GeV. Four and eight millimeters thick tungsten crystals and a compound target made of a 4 mm crystal followed by a 4 mm amorphous disk were used with an orientation along the 〈1 1 1〉 axis. The positrons were detected by a drift chamber, partially immersed in a magnetic field. The reconstructed trajectories allowed the determination of their energy and angular spectra. Significant enhancements were observed for the crystal source when compared to the amorphous one. The gain was about 3 for the 4 mm target and about 2 for the 8 mm and the compound targets. These preliminary results are described after short presentations of the experimental set-up and of the method of track reconstruction.

We investigated the laser-induced fluorescence spectra (LIF) of porcine cardiac tissues with different degrees of viability. The data obtained are compared with the results of routine histological investigations and also with the experiments performed with the use of fluorescent probes. It has been found with a high degree of reliability that the loss of the viability of the myocardium tissue leads to the alteration of its LIF spectra. This can be used for low-invasive rapid control of transplant viability in the process of its preparation and during surgery.

The influence of the strictive self-interaction on the threshold and quality of phase conjugation in the course of stimulated Brillouin scattering (SBS) was investigated numerically in the linear approximation for steady-state linearly polarised pumping. The calculations were carried out for the three-dimensional case of a Gaussian pump beam and a beam representing a superposition of 10 x 10 Hermitian - Gaussian modes with random phases. It was found that in the case of a Gaussian beam the growth of the strictive aberrations leads to a significant reduction of the SBS threshold but has little influence on the conjugation quality. In the case of a pump beam with a divergence exceeding the diffraction limit such growth of the strictive aberrations results (on the average) in lowering the SBS threshold and in deterioration of the conjugation quality. The calculated results depend strongly on the specific phase combination of the superposed modes. (nonlinear optical phenomena)

Laser-induced fluorescence (LIF) spectra of human cardiac-valve tissues affected by calcinosis and of macroscopic calcinosis formations produced from resected cardiac valves with such pathology were investigated by comparison with analogous spectra of bone and myocardial tissue of an animal, LIF was excited by an excimer laser with λ=248 nm. In the spectrum of macroscopic calcinosis formations, luminescence bands of the mineral component were separted from the band of protein tissues when these tissues were subjected to heat treatment at 700°C. The investigations have shown that the LIF spectrum of a calcified tissue contains fluorescence bands of tryptophan and fluorescence bands of the mineral component (hydroxylapatite). A change in the spectrum of tissues with pathological processes can be cause not only by a relative change in the concentration of collagen elastin, but also by the additional fluorescenced of the hydroxylapatite mineral that is absent in a healthy cardiac tissue. It was found that the change in the spectrum characterized by the ratio of the LIF intensity at λ=330 nm to the LIF intensity at λ=450 nm is sufficiently large. This makes it possible to use measurements of the relative intensity of fluorescence at these wavelengths to control the degree of calcination of cardiac tissue.

Results of cerebral hemodynamics condition assessment in dependence on central hemodynamics and biological aging rate are given in the article. Peculiarities of blood flow which influence on the development of chronic brain ischemia and mechanisms of its cellular compensation are revealed.

A numerical investigation is reported of the influence of the thermal self-interaction of a Gaussian pump beam on the quality of phase conjugation by stimulated Brillouin scattering (SBS). A laser pulse is assumed to be sufficiently long to apply the equalised pressure approximation in calculating the acoustic field. All the calculations are carried out in a three-dimensional formulation for focused beams making use of an approximation linear in respect of the pump intensity. It is confirmed that the growth of thermal perturbations increases the SBS threshold and lowers the phase conjugation quality. A comparison of the calculated and published experimental results shows that they are in satisfactory quantitative agreement. (nonlinear optical phenomena and devices)