Search

Background. It is shown that it is necessary to study the effect of atmospheric turbulence on the spectral characteristics of a radio signal. Aim. The influence of atmospheric turbulence on the spectral fluctuations of the radio signal intensity and on the displacement of the spectral components of the radio signal has been studied. Methods. The research was carried out on the basis of an analysis of the relationship between two-wave and single-wave correlation ratios. Based on the solution of the differential equation for fluctuations of the eikonal amplitude of an electromagnetic wave and the use of the derived trigonometric ratio, a connection between the two-wave Fourier=spectrum and single-wave spectra is obtained. In this case, a single source of turbulence effects on the radio signal was used at the coordinate point of the radio wave propagation by introducing a new variable equal to the average value of the coordinates of the turbulence effect. To find the resulting double integral, one of the coordinates of the turbulent action is transformed into an angular variable. Results. The dependence of the relative dimensionless mean of square of the integral intensity of the radio signal fluctuations on the wave number of turbulent pulsations of the atmosphere at various displacements of the spectral wavelengths of the radio signal is found. Conclusion. It is shown that turbulence slightly distorts the spectral information essence of a propagating radio signal in various wavelength ranges.

Background. It is necessary to study the influence of the physical characteristics of the atmosphere, in particular, wind on atmospheric turbulence and, consequently, on the characteristics of the radio signal it is shown. Aim. The dependence of the time-spectral function of the radio signal energy flux on the wind speed in the troposphere in the antenna plane is found. Methods. A method of transition from the Cartesian coordinate system in the antenna plane to the polar coordinate system of wave numbers has been developed. Based on this method the relationship between the Fourier spectral function of the correlation moment and the representation of the Bessel function is found. For the Fourier spectral function of the correlation moment, the previously obtained solution of the differential equation for the fluctuations of the eikonal amplitude of electromagnetic wave in a turbulent atmosphere at the front of the electromagnetic wave at the coordinate of the receiving antenna is used. Using the inverse Fourier transform the relationship between the time-spectral function of the radio signal energy flux and the time-correlation function of this flux is found. Results. Based on the study of the time-correlation function of the radio signal energy flow its relationship with the two-point correlation moment characterizing the fluctuations of the eikonal amplitude of the radio signal is found. To analyze the effect of wind, a turbulence model was used, reflecting the inertial turbulence interval, in which the energy flow from larger turbulent vortices to smaller vortices is determined by the viscous dissipation of the smallest vortices. Conclusion. Numerical calculations have shown that such a wind in the antenna plane blows away turbulent vortices in this plane, bettering the quality of the received radio signal.

Background. Interest in the biological effects of electromagnetic radiation on biological objects is associated with the possibility of their use in solving a number of fundamental and applied problems: from the consideration of biological feedbacks in real time, which allows the development of electronic medical complexes, to the creation of neuro-computer interfaces, including components of living cells. Aim. The paper shows the development of a device for influencing biological objects with a permanent magnetic field, which allows modeling the basic parameters of the physical factor, for conducting a magnetobiological experiment with normalization of the effects of non-ionizing radiation of the specified parameters. Methods. The device for influencing biological objects of constant magnetic field allows to obtain, in a large volume, the most homogeneous magnetic field. Results. Mathematical modeling of changes in the morphofunctional state of the adrenal cortex according to eleven biological parameters at different periods of exposure to normalized constant magnetic field when exposed to the maximum permissible level was evaluated by the deviation of the interval indicator and its normalized value. The effect of this factor led to a deviation of the integral index in the glomerular zone of the adrenal glands on the 30th day was – 6,53 ± 1,30*10-2, later on the 60th day the deviation increased by 8,28 ± 1,55*10-2, on the 90th 4,84 ± 1,50*10-2, then on the 120th day, it did not differ from normalized. Conclusion. After the termination of the constant magnetic field in a series of 15–30 mT experiments, the morphofunctional state of the thymus returned to normal. Thus, the device is recommended for use in experimental activities.

Background. Turbulent fluctuations of the refractive index in the atmosphere lead to distortions during the passage of the radio signal. This can lead to distortion of the transmitted information due to the resulting fluctuations of the amplitude, phase and intensity of the electromagnetic wave that transmits the radio signal. Fluctuations in the intensity of the radio signal lead to flickering of the radio signal on the receiving antenna due to turbulent phenomena in the atmosphere, which are a complex multifunctional physical phenomenon. Aim. The problem of fluctuation of the intensity of the radio signal at the receiving antenna due to atmospheric turbulence is considered – the flicker of the radio signal. This problem is currently extremely actual, because there is a tendency of active, negative interference in the process of high-quality transmission of the radio signal on the background of naturally caused turbulent fluctuations. Methods. A theoretical analysis of the passage of a radio signal through a turbulent atmosphere is carried out. The spatial correlation function of fluctuations in the intensity of the received radio signal due to atmospheric turbulence is investigated. Results. The concept of the radio signal flicker characteristic is introduced as the average value of a random variable over the cross section of the receiving antenna – the dispersion of the logarithm of the radio signal power. A model of the occurrence of fluctuations in the case of two regions in the cross section of the receiving antenna with different levels of radio signal intensity is calculated. The correlation function for this model is found. Conclusion. Based on the Fourier-spectrum expansion of the two-point spatial correlation function of turbulent fluctuations of the refractive index, the dependence of the flicker characteristic of the radio signal on the wave number of turbulent fluctuations of the atmosphere is found. It is shown that the turbulence of the atmosphere has the greatest effect on the radio signal when the length of the electromagnetic wave is comparable to the scale of turbulent fluctuations.

Interaction of an electromagnetic wave, as the determined wave process spreading in an atmosphere and atmospheric turbulence, as stationary stochastic wave process is considered. The differential equation for eikonal fluctuations of an electromagnetic wave is received. On basis of this equation the occurrence of amplitude and a phase fluctuations of an electromagnetic wave at distribution of a radio signal into a turbulent atmosphere is investigated. In particular the differential equations for fluctuations of amplitude and a phase of the electromagnetic wave caused by turbulent pulsations of a parameter of an atmosphere refraction are received and solved. Fourier-spectra of two-point correlations of a parameter of an atmosphere refraction, amplitude and a phase of an electromagnetic wave are considered. Are received also by a method of introduction of Green’s function the differential equations for these correlations are solved. On basis of the analysis of various wave ranges of an atmospheric power spectrum of turbulence the dependences of amplitude and a phase Fourier-spectra of a radio signal on parameters of an electromagnetic wave and turbulence of an atmosphere are found.

On the basis of the solution of Maxwells equations system for electromagnetic radiation in a turbulent atmosphere the differential effective section of scattering of this radiation on turbulence is found. Dependence of scattering section on wave length and an angle of scattering is investigated. It is shown that interaction of electromagnetic radiation and turbulence of an atmosphere is interaction of the determined electromagnetic wave process with stochastic turbulent wave process. It is marked, that the wave vector of scattering electromagnetic radiation is proportional to a wave vector of turbulence.

The kind of a hydrostatic equation for the vertical elastic tank, for example, a fuel tank of a rocket on a starting table is proved. The hydrostatic equation is received on the basis of specified Bernoullis equation. The substantiation is lead with the help of Laplaces formula for pressure under an elastic surface of a liquid which can arise both due to forces of a superficial tension, and due to an elastic thin-walled shell as in the present task. The form of the vertical elastic tank with a rigid bottom and the rigid top band, filled with a lied liquid is received. It is shown that it is necessary to use special record of the Gooks law for reception of the form of the tank. The analysis of this form is carried out. Distribution on height of the tank of hydrostatic pressure, volumetric density of energy of the stretched elastic wall, and also the sum of these sizes is shown. Hydrostatic pressure at which level there is a maximal increase in the area of the elastic tank is found.

Waveguide structures are used to transmit energy and information signals in a wide range of wavelengths and, in terms of wave-guiding physical properties, usually have mutual (identical) properties in forward and backward directions. The asymmetry of the structure and external influences can often cause non-reciprocity of structures for waves, propagating in mutually opposite directions (this property, although limited, is already used in the so-called nonreciprocal devices of microwave, EHF and optical ranges such as ferrite valves, circulators, phase shifters). At the same time, the nonreciprocal properties of wave-guiding structures, independent of their physical nature, were not considered. It is found, that the motion of the medium filling the acoustic waveguide leads to nonreciprocity of its parameters in the forward and backward directions. The degree of nonreciprocity is proportional to the velocity of the medium. The velocity of the medium also affects the propagation velocity of acoustic waves and leads to a change in the critical frequencies or critical wavelengths of the waveguide modes. As the velocity of the medium increases, the number of modes for which the propagation condition is satisfied increases as well.

The principle of calculation of a plate from a metamaterial with inductive type chiral inclusions is submitted. It is shown that distribution of an electromagnetic wave to such substance can be investigated with the help of introduction of a chiral parameter and on the basis of a detailed method of calculation. By comparison of two methods the dependence of chiral parameter from frequency of electromagnetic radiation falling on a plate is found. With the help of a detailed method the nonlinear differential equation for potential on the chiral plate is found. It is shown that this equation has solutions as traveling solitary and standing waves but not traveling sine waves. The analysis of the received solutions of the nonlinear equation is carried out. Transition from the multiwave solution to the solution as standing waves is graphically shown at reduction of distance between the chiral elements.

The solution of the genetic-mathematical problem of interaction between the human population and the virus population in relation to the problem of the COVID-19 pandemic is presented. It is noted that the virus does not interact with the entire human body, as a set of complex organs, but with its individual cells. A mathematical model based on the HardyWeinberg law is used, consisting of two linear interdependent differential equations relatively to the frequency of an allele with different right sides. The equations reflect the time dynamics of human cells and virus populations during their interaction. In the equation for the virus population the right side is a constant value that characterizes the death of viruses due to the human immune system. In the equation for human cells population the right side depends linearly on the allele frequency of the virus population. The right side of this equation characterizes the death of a cell when a virus inserted in its DNA for its reproduction. Solutions of differential equations are found and the results of these solutions are analyzed. The duration of the pandemic was estimated using parameters of human liver cells and influenza virus.

A mimetic of the BDNF loop 4, bis (N-monosuccinyl-L-seryl-L-lysine) hexamethylenediamide, named GSB-106, was designed and synthesized in our scientific group. The compound activated TrkB, MAPK/ERK, PI3K/AKT, and PLCγ in in vitro experiments. In vivo experiments with rodents revealed its antidepressant-like activity in the forced swim and the tail suspension tests at the dose range of 0.1–5.0 mg/kg (i.p., p.o.). However, GSB-106 was not studied in depression models modulating major depression in humans. In the present study, the GSB-106 antidepressant-like activity was revealed in mice at the depression model induced by 28-day social defeat stress with 21-days oral administration (0.1 mg/kg) after stress. At the same time, GSB-106 restored reduced locomotor activity and completely eliminated the anhedonia manifestations. The compound also restored reduced levels of synaptophysin and CREB in the hippocampus. In addition, the Trk receptor antagonist K252A, and the PLC inhibitor U73122, were found to completely block the antidepressant-like activity of GSB-106 in the forced swimming test in mice. Thus, the present results demonstrate the dipeptide BDNF mimetic GSB-106 reversed depressive-like behavior and restored hippocampal neuroplasticity in a rodent depression model. These effects of GSB-106 are probably regulated by TrkB signaling.

The article is devoted to the analysis of existing domestic and foreign methods for assessing the probability of bankruptcy of organizations in the region. When assessing the financial stability of the entity’s enterprises, various methods are used to assess the financial stability of an organization, the most common approach of which is the coefficient method. However, methods that use factor analysis, which builds a linear dependence of indicators of the financial and economic condition of a regional subject, are gaining popularity. These models are also called bankruptcy prediction models. One of the most popular models is Altman’s five-factor forecasting model and the four-factor model for non-manufacturing organizations. Altman’s approach is simple and versatile. However, this Altman model does not take into account the individuality of the company. British scientists G. Tishaw and R. Taffler modernized Altman’s model. One of the first Russian models for predicting the bankruptcy of economic entities was developed by A.Yu. Davydova and A.Yu. Belikov. This model took into account the relationship between such factors as working and equity capital, assets, net profit, cost and revenue. The following model, showing the financial stability of an enterprise, was formulated by Savitskaya. From the analysis of existing methods and models for assessing the financial and economic condition of regional economic entities, it follows that it is advisable to build a model taking into account: firstly, the individual characteristics of a particular organization; secondly, the choice of indicators and their weighting coefficients in the model must be scientifically justified. Therefore, the paper proposes to determine the financial stability of an organization in the region to form a model that includes the most commonly used in practice, namely the above five models for assessing the probability of bankruptcy of enterprises. At the same time, the industry specifics of organizations were taken into account. The purpose of the study is to form a methodology for assessing the integral level of financial stability of organizations in the region and determining the possible boundaries of its variation. In the course of the study, such methods as comparative, component and factor analysis, experiment were used. The paper presents a methodology for the formation of a generalized factor model for assessing the level of financial condition of regional organizations. The critical values of the integral indicator characterizing the level of financial condition of organizations are also determined.

Background. Kaposi sarcoma is a low-grade vascular tumor affecting blood and lymphatic vessels associated with the human herpes virus type 8 (HHV-8). As a rule, the skin of the lower extremities is involved in the process first of all, and then other organs and lymph nodes are involved. There are 4 various types of the disease with different clinical picture: the classic, the endemic, the epidemic and immunosuppression subtype. The epidemic subtype is the most common and has the most aggressive course, with specific lesions of a multiple kind, including the skin, mucous membrane layers, the lymph nodes, the gastrointestinal tract, the lungs and the spleen. Osseous metastases are extremely rare. Aim. Show the case of Kaposi sarcoma with osseous metastases in patient with the human immunodeficiency virus (HIV) infection. Results. We observed a 43-year-old patient with HIV infection and stage 4b Kaposi sarcoma against the background of the irregular antiretroviral therapy in the progression stages. The duration of the anamnesis was 32 months. The clinical debut of the cancer process was noted with skin lesions on the shoulder. Histological and immunohistochemical analysis of skin biopsies showed the morphological picture of Kaposi sarcoma. HHV-8 was expressed in tumor cells. During the endoscopic examination the lesions of oral mucosa, stomach and proximal colon were confirmed morphologically, and spiral computed tomography of the chest revealed the lesions in the lungs. On this point, the patients received oxaliplatin-based chemotherapy and aetoposidum for 6 months and against the background of this treatment we observed the disease progression associated with the involvement of the retroperitoneal lymph nodes, the left adrenal gland and the penis. Circumcision was performed in the case associated with the involvement of the penis. The treatment was continued. The lytic left iliac bone lesion, the retroperitoneal lymph nodes, the iliac lymph node groups, as well as the left inguinal lymph nodes, the left adrenal gland and the lungs were characterized by a high F-18 FDG uptake after 3 months of the treatment, according to the results of Fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography combined with computed tomography (PET/CT). Conclusion. Kaposi sarcoma in patients with HIV infection had an aggressively course with disseminated skin lesions and internal organ involvement, including bones as showed in this clinical case. In this case, the axial skeleton was more commonly involved. PET/CT is a diagnostic imaging method in the differential diagnosis and determination of the prevalence of the cancer process.

Background. Breast cancer is the leading cause of death in women. Distant metastases in different organs, including the thyroid gland, are still an urgent problem. Distant metastases are very rare in clinical practice. Nevertheless, the accumulated clinical and surgical experience in treatment has shown that breast cancer is the second most common primary tumor, leading to thyroid gland metastases, after kidney cancer. Aim. Present the clinical observations of synchronous thyroid gland metastases from breast cancer. Materials and methods. We observed two patients, aged 55 and 72 years, suffering from metastatic breast cancer with simultaneous metastases to the thyroid gland, to the cervical and mediastinal lymph nodes, to the lungs, to the ovaries and to the bones. Results. A 55-year-old woman with a left sided neck mass and hoarseness has been suffering from the metastatic breast cancer with simultaneous metastases to the thyroid gland, to the cervical lymph nodes, to the lungs, to the ovaries and to the bones. The biopsy of the primary tumor has been performed. The tumor has the structure of invasive ductal carcinoma, G2, luminal A subtype, HER2-negative type in histological and immunohistochemical analysis. The spread of the tumor has been determined by positron emission tomography/computed tomography (PET/CT). Metastases from breast cancer have been cytologically proven during thin needle biopsy. A 72-year-old woman with a mass in the region of thyroid gland has been suffering from breast cancer with metastases to the thyroid gland, to the mediastinal and cervical lymph nodes, to the bones, and to determine this process PET/CT, the thyroid fine needle aspiration biopsy and core biopsy of primary tumor have been applied. The histological variant was represented by invasive ductal cancer, G2, luminal A subtype, HER-2 negative type. Taking into account the spread of the process, the patients were given polychemotherapy, targeted therapy and hormone therapy. There is no disease progression for 6 months. Conclusion. Synchronous thyroid gland metastases in case of primary breast tumors are rare. In such cases, PET/CT is the important diagnostic method. The main therapeutic option in this case is systemic therapy, including chemotherapy, targeted and hormone therapy, the nature of the agent depends on the biological variant of the tumor.

Isolated splenic metastases from colorectal cancer after radical surgical treatment are quite rare. This frequency of metastases is explained by the anatomical, functional and immunological characteristics of the spleen. The literature usually describes single clinical cases followed by accompanied systematic analysis and discussion. Most of the cases are asymptomatic and are accidentally diagnosed, during different types of imaging tests, including increased levels of tumor markers. The progression free survival was 3 144 months after surgical treatment of the primary tumor in most of the patients. By the nature of the lesion, metastases can be synchronous and metachronous, as well as solitary and multiple. Aim. To discuss two clinical observations of isolated splenic metastases in patients after left colic flexure cancer surgical treatment. Materials and methods. We observed 2 female patients, 68 and 70 years old, with isolated splenic metastatic after left colic flexure cancer radical surgical treatment. Results. Both cases are considered to be metachronous and the interval of absence of disease manifestations are 21 and 10 months, respectively. The patients with stage IIB and IIC left colic flexure cancer underwent left hemicolectomy followed by adjuvant polychemotherapy using regimen with 6 cycles of FOLFOX. The histological study revealed a moderately differentiated adenocarcinoma with invasion into all layers of the wall and into the surrounding tissue. There were no lymph node metastases. In the course of dynamic observation, during the next examination with the help of ultrasound examination we revealed splenic metastasis, and confirmed this using positron emission tomography/computed tomography. The disease was without clinical picture. The time interval after the surgery before diagnosis was 21 and 10 months, respectively. Surgery was performed in the volume of splenectomy. Isolated splenic metastases in the absence of other manifestations of the disease were found intraoperatively. The histological study showed the splenic metastasis of the same type of cancer as the primary tumor. The polychemotherapy using regimen with 6 cycles of XELOX was performed during the postoperative period. Patients are alive without signs of the disease over the period of 5 and 26 months, respectively. Conclusion. Isolated splenic metastases are extremely rare, more often when the primary tumor is located in the left side of the colon. The showed cases illustrate the need and importance of the monitoring the patients after surgical treatment for colon cancer. The use of positron emission tomography/computed tomography helps to understand the real prevalence of the tumor process, without using invasive methods. The surgery in the volume of splenectomy followed by chemotherapy are the main therapeutic options. In one clinical case, the metastases were multiple, and in the other one was solitary metastasis. Patients are alive without signs of the disease over the period of 5 and 26 months, respectively.

Introduction. Brain metastases can occur in almost all gynecological malignancies and, despite modern therapeutic options, have a poor prognosis. Brain metastases from vulvar cancer are considered to be rare. In the literature, the reports on these cases have identity character. The aim is to show clinical observation of the patient with vulvar cancer with brain metastases. Results. Patient S., 60 years old, with stage I р T1N0M0 vulvar cancer underwent vulvectomy in January 2018. During the histological study in the subepithelial layers were the areas of kraurosis with the growth of squamous cell keratinous carcinoma. Taking into account the prevalence of the tumor process, adjuvant treatment was not carried out. Two years later, in January 2020, there were focal symptoms in form of weakness in the left upper and lower limbs, an unsteady gait, a generalized weakness. During magnetic resonance imaging (MRI) of the brain in the occipital lobe paraventricular with intensive perifocal edema to the right was determined cystic-solid formation with rough edges which size was 293365 mm without clinically significant mass-effect. The middle structures were not displaced. Positron emission tomography-computed tomography (PET/CT) was performed to detect the prevalence of the tumor process. Data on the presence of the active specific process at the time of study were not received. Taking into account the absence of other indicators of generalization process, whole brain radiation therapy (single fraction dose of 3 Gy, total radiation dose of 30 Gy) was carried out, followed by the application of Temodal. The patient was examined in 6 months. There were no signs of progression. Conclusion. Brain metastases from vulvar cancer are considered to be rare. This clinical case is interesting because brain metastases have been the only manifestation of the progression of the tumor process in the absence of regional lymph nodes damage. The main diagnostic method is MRI of the brain. The use of PET/CT helps to detect the prevalence of the tumor process. The metastases have been detected after 36 months from the date of the initial diagnosis of the cancer. Radiation therapy is a method of choice of brain metastases treatment.