Signal Formation Research Articles

Unveiling the Dynamics of KRAS4b on Lipid Model Membranes

Small GTPase proteins are ubiquitous and responsible for regulating several processes related to cell growth and differentiation. Mutations that stabilize their active state can lead to uncontrolled cell proliferation and cancer. Although these proteins are well characterized at the cellular scale, the molecular mechanisms governing their functions are still poorly understood. In addition, there is limited information about the regulatory function of the cell membrane which supports their activity. Thus, we have studied the dynamics and conformations of the farnesylated KRAS4b in various membrane model systems, ranging from binary fluid mixtures to heterogeneous raft mimics. Our approach combines long time-scale coarse-grained (CG) simulations and Markov state models to dissect the membrane-supported dynamics of KRAS4b. Our simulations reveal that protein dynamics is mainly modulated by the presence of anionic lipids and to some extent by the nucleotide state (activation) of the protein. In addition, our results suggest that both the farnesyl and the polybasic hypervariable region (HVR) are responsible for its preferential partitioning within the liquid-disordered (Ld) domains in membranes, potentially enhancing the formation of membrane-driven signaling platforms.Graphic

Development of a module for an automated diagnostic system for antibodies G and M

The infectious disease COVID-19 occurs as a result of infection with the SARS-CoV-2 coronavirusstrain. Most often, COVID-19 proceeds with signs of an acute respiratory viral infection (ARVI) (fever, cough, body aches); loss of smell, nausea, and shortness of breath are possible. However, in a large percentage of those infected, the course of the disease is asymptomatic. After the virus entry into the body, the immune system begins to produce antibodies specific to this virus (Ig - immunoglobulins) - an important factor in the formation of the immune system’s defense against infection. Antibody testing is recommended as an additional method for diagnosing an acute infection or when it is impossible to study smears by amplification of nucleic acids, to identify individuals with an asymptomatic form of infection, to establish the fact of a previous infection, and also to select potential donors of immunocompetent plasma. Determination of antibodies of different classes in the blood is informative evidence of the current or past infectious process and helps to identify the stage of the infection development. More often, the level of antibodies of class M (IgM) and G (IgG) is determined in the blood. The development of the instrument base of express analyzers for monitoring the presence of antibodies to the new coronavirus infection COVID-19 is currently relevant in connection with the emerging and ongoing pandemic. It is possible to use the following systems as test analyzers for immune enzyme medium: ARCHITECT – IgG, Abbott and ELISA-IgM-BEST. For the hardware, an Omron industrial controller and CX-One programming system can be used. The truth table for the formation of signals on the diagnosis of the disease has been developed to obtain logical equations for the operation of the analyzer module. The synthesis of relay-contact circuits has been carried out. The simulation of the module’s operation showed satisfactory results. Timely and correct diagnostic measures make it possible to diagnose and assess the severity of the disease as early as possible.

The Formation of Signal Construct of Complex Structures with a High Level of Uncertainty in Their Parameters

Radio communication systems with enhanced resistance to illegitimate influences are of great interest in the development of modern information technologies. The modern methods of implementing such radio systems are the technologies of cryptographic information protection, methods of direct spectrum expansion. Despite the achievements of the selected subject area, the practical implementation of radio systems of this level is hampered by models of radio communication channels. Known results in their totality do not take into account the potential capabilities of implemented modulation formats, which limits their practical application and indicates the relevance of the study. The aim of the scientific work is to formalize theoretical principles and approaches to the formation and evaluation of the effectiveness of signals of complex structure. The authors posed and solved the problem of a formalized presentation of the obtained solutions, conducted a critical analysis of the results obtained by different methods. In this case, methods of statistical radio engineering, harmonic analysis of discrete signals, random graph theories, and decision making were used. The authors conducted a simulation of the processes of manifestation of various structures of the generated signals. The coincidence of theoretical and practical results is substantiated. During the study, the properties of signals of complex structures were determined. A theoretical statement is formulated and proved that justifies the increase in the structural secrecy properties of the generated radio signals. The novelty of the approach is the use of random graph theory, which has reduced the complexity of the evidence base, the stages of simulation. The theoretical results obtained are critically evaluated in relation to the final modeling data, which made it possible to substantiate the adequacy of the results. The obtained solutions substantiate theoretical approaches to the formation of signal construct of complex structure. In contrast to the known studies, the study reveals the potential stability boundaries of radio systems based on signals with uncertain parameters. The theoretical significance of the presented results is the expansion of the practical implementation of the methods of the general theory of communication in the field of building noise-immune systems. Practical significance is based on the results of analytical and simulation modeling presented in the work.

Peculiarities of Constructing a Scheme for Formation of a Microwave Excitation Signal in a Cesium Atomic Clock

In this paper, we determine the formation peculiarities of a microwave excitation signal in the quantum frequency standard on cesium-133 atoms. To improve the characteristics of the microwave excitation signal, a method for optimizing the parameters of blocks and schemes of a quantum frequency standard with allowance for the established features is proposed. The studies showed that the use of this method can improve the spectral characteristics of the microwave excitation signal and reduce the step of tuning its output frequency. The experimental results allowed establishing that the use of this method improves the output frequency stability of the quantum standard by 20%. The established peculiarities create conditions for new research aimed at developing methods and techniques for improving the characteristics of the microwave excitation signal.

Identification of the EPR signals of fig leaves (Ficus carica L.)

The article is devoted to the study of the leaves of the fig (Ficus carica L.) tree is one of the most valuable trees of the Absheron Peninsula (Azerbaijan). Research on fig leaves growing in Mardakan and Nardaran areas of Absheron has been carried out on EPR spectrometer. Studies have shown that stressors cause the formation of nanophase particles of biogenic origin in living systems. These nanoparticles lead to the formation of magnetic properties in biological systems and the formation of the broad EPR signal that we first discovered in plants. It was found that the magnetic properties depend on the type of plant and the environmental conditions in which they live and the characteristics of EPR signals characterizing magnetic nanoparticles (amplitude, signal width, g factor, etc.) are strongly dependent on temperature and that this signal has magnetic anisotropy. Studies of fig leaves have shown that as a result of biomineralization under stress, they form magnetic nanoparticles of iron oxide. In addition, the high intensity of the broad EPR signal characteristic of nanophase magnetic particles detected in fig leaves growing in Mardakan area (Azerbaijan) indicates that the plant system in this area is more exposed to pollutants and the area is more environmentally polluted than Nardaran Area (Azerbaijan). The characteristic verve phase transition occurs at a temperature of 120-125 K in the behavior of parameters such as the amplitude of the magnetic resonance signal and the width of the magnetic resonance line. The results were confirmed by the messabauer method.

Multielement Analysis of Oil by ICP–AES and ICP–MS with Microwave-Assisted Sample Preparation

To obtain detailed information on the elemental composition of oil, we developed ICP–AES and ICP–MS procedures for the determination of a wide range of elements in oil after microwave sample digestion. We found a possibility and selected the conditions of the microwave decomposition of samples of light and superviscous oils, weighing up to 1000 mg. The effect of residual acidity and residual carbon on the formation of an analytical signal in ICP–AES and ICP–MS (high resolution) was studied. We found that 20 elements can be determined by ICP–AES at a level of n × 10–2–m × 102 μg/g and 42 elements can be determined by ICP–MS at a level of n × 10–2–m × 102 ng/g.

Signal Origin of Electrochemical Strain Microscopy and Link to Local Chemical Distribution in Solid State Electrolytes.

Electrochemical strain microscopy (ESM) is a distinguished method to characterize Li-ion mobility in energy materials with extremely high spatial resolution. The exact origin of the cantilever deflection when the technique is applied on solid state electrolytes (SSEs) is currently discussed in the literature. Understanding local properties and influences on ion mobility in SSEs is of utmost importance to improve such materials for next generation batteries. Here, the exact signal formation process of ESM when applied on sodium super ionic conductor (NASICON)-type SSE containing Na- and Li-ions is investigated. Changes in the dielectric properties, which are linked to the local chemical composition, are found to be responsible for the observed contrast in the deflection of the cantilever instead of a physical volume change as a result of Vegard´s Law. The cantilever response is strongly reduced in areas of high sodium content which is attributed to a reduction of the tip-sample capacitance in comparison to areas with high lithium content. This is the first time a direct link between electrostatic forces in contact mode and local chemical information is demonstrated on SSEs. The results open up new possibilities in information gain since dielectric properties are sensitive to subtle changes in local chemical composition.

Theoretical Analysis of PAPR Companding Techniques for FBMC Systems

The offset quadrature amplitude modulation (OQAM) with filter bank multicarrier (FBMC) has turn on considerable interest in last decades over orthogonal frequency division multiplexing (OFDM) because of their a significant number of advantages. However, largest peak to average power ratio (PAPR) minimization techniques developed for OFDM systems may not be applicable directly for OQAM-FBMC systems, due to the super-imposed formation of OQAM-FBMC signals. In this article, the issue of power ratio reduction technique is address theoretically and complementary cumulative distribution function for OQAM-FBMC systems using various companding transforms are analyzed. Theoretical analysis and simulation results shows that the $$\mu$$ -law companding method is efficiently reduced PAPR among all other companding techniques.

Ultrafast laser-induced guided elastic waves in a freestanding aluminum membrane

Ultrafast laser-induced guided acoustic waves in thin, freely suspended films are important for many applications adopting the laser-ultrasonics technique. These waves show unique dispersion relations, leading to minimal propagation losses and acoustic energy confinement. While this principle has been known, the separation of various physical effects in the formation of measured signals involving these guided acoustic waves has not been clearly elaborated. Here, we present a combined experimental and theoretical study on all-optical excitation and detection of these waves in a thin, freestanding aluminum membrane. The acoustic dynamics is excited and measured by using a femtosecond time-resolved pump-probe technique with controlled probing position, enabling spatially resolved detection. The measured signals are compared with an advanced numerical model that we developed earlier [H. Zhang et al., Phys. Rev. Appl. 13, 014010 (2020)], showing excellent agreement. The combination of experiment and simulation allows us to decode various physical effects in the signal formation, including different acoustic field components. Unknown material properties, such as acoustic attenuation coefficients, and the two complex photoelastic constants are quantitatively retrieved by fitting the measured signals. Furthermore, we provide evidence of nonlinear propagation of the excited guided acoustic waves.

Radiation-Induced Bystander Effect: Loss of Radioprotective Capacity of Rosmarinic Acid In Vivo and In Vitro.

In radiation oncology, the modulation of the bystander effect is a target both for the destruction of tumor cells and to protect healthy cells. With this objective, we determine whether the radioprotective capacity of rosmarinic acid (RA) can affect the intensity of these effects. Genoprotective capacity was obtained by determining the micronuclei frequencies in in vivo and in vitro assays and the cell survival was determined by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay) (MTT) assay in three cell lines (PNT2, TRAMPC1 and B16F10), both in direct exposure to X-rays and after the production of radiation-induced bystander effect. The administration of RA in irradiated cells produced a decrease in the frequency of micronuclei both in vivo and in vitro, and an increase in cell survival, as expression of its radioprotective effect (p < 0.001) attributable to its ability to scavenge radio-induced free radicals (ROS). However, RA does not achieve any modification in the animals receiving serum or in the cultures treated with the irradiated medium, which expresses an absence of radioprotective capacity. The results suggest that ROS participates in the formation of signals in directly irradiated cells, but only certain subtypes of ROS, the cytotoxic products of lipid peroxidation, participate in the creation of lesions in recipient cells.

Raman scattering model of the spin noise.

The mechanism of formation of the polarimetric signal observed in the spin noise spectroscopy (SNS) is analyzed from the viewpoint of the light scattering theory. A rigorous calculation of the polarimetric signal (Faraday rotation or ellipticity) recorded in the SNS is presented in the approximation of single scattering. We show that it is most correctly to consider this noise as a result of scattering of the probe light beam by fluctuating susceptibility of the medium. Fluctuations of the gyrotropic (antisymmetric) part of the susceptibility tensor lead to appearance of the typical for the SNS Faraday rotation noise at the Larmor frequency. At the same time, fluctuations of linear anisotropy of the medium (symmetric part of the susceptibility tensor) give rise to the ellipticity noise of the probe beam spectrally localized at the double Larmor frequency. The results of the theoretical analysis well agree with the experimental data on the ellipticity noise in cesium vapor.

Features of the Formation and Processing of Signals in an Autodyne Radar with Frequency Modulation Taking into Account the Nonlinearity of the Modulation Characteristic

The results of the study of the features of the formation and processing of signals of autodyne short-range radar systems (SRR) with frequency modulation (FM) involving non-linearity of the modulation characteristic are presented. The numerical simulation of the nonlinear influence of the modulation characteristic on the shape and spectrum of the autodyne signal is implemented on the basis of the mathematical model of the autodyne generator. We have established that even a small non-linearity of this characteristic causes a significant distortion of the shape and spectrum of the autodyne signal. A method of quasi-static correction of the law of frequency modulation of probing radiation using a digital signal processor is proposed, which does not require complication of the microwave part of the autodyne SRR with FM. The results of experimental studies of an 8-mm autodyne SRR made on the basis of a Gann diode oscillator with frequency control by varicap are presented.

Algorithms for the automated construction of control matrices of input and output electrical signals when monitoring the functioning of electrical systems of special equipment products

Controlling the functioning of special equipment is the most important task both at the stage of prototyping and testing, and at the stage of operation. Functional control is understood as checking the electrical interaction of the systems of a special equipment product with each other in accordance with the relevant interaction protocols. At present, the improvement and development of new algorithms for the automated construction of control matrices of input and output signals, which, if necessary, change the logic of the electrical systems of the control object (changing the time of receiving or issuing electrical signals), will require minimal, nonresource-intensive adjustments during software debugging. is the most urgent technical problem in this topic. This article analyzes the control modes using a minimal set of initial data – the formation times of input and output electrical signals, which are completely determined by the protocols of interaction of control systems with the controlled object, and algorithms are determined that automatically generate control matrices of input and output signals. The presented block diagrams of algorithms allow you to form a zero control matrix, as well as determine the maximum key clock moment, using two mathematical matrices describing the input and output signals, while the interaction of special equipment product systems with external control systems at key clock moments is described by a transition graph. The proposed mathematical expression systems are adaptive in the event of serious changes in the operation of the systems of the object of control (or control systems), while the construction of algorithms according to the principles given in this article (the use of standard blocks performing specific tasks) will also make it easy to take into account the change in the form of the initial data. Regularities in the formation of input and output signals are revealed on the basis of the analysis of control over the functioning of various products of special equipment. If it is necessary to change the logic of the operation of the electrical systems of the controlled object (changing the time of receiving or issuing electrical signals), it is enough to correct the initial data, on the basis of which the control matrices of the input and output electrical signals will automatically change, which significantly reduces the software debugging time. Thus, the task of the developer of control modes is reduced to setting the minimum set of initial data – the times of formation of input and output electrical signals, which are completely determined by the protocols of interaction of control systems with the controlled object, then the developed algorithms allow automatically generating control matrices of input and output signals.

Модулятор для здійснення амплітудної модуляції багатьох складових

The authors consider various anti-noise techniques in systems using digital signals, in particular QAM (quadrature amplitude modulation) signals. To increase the noise immunity of a system, it is proposed to use amplitude modulation of many components (AMMС). The advantages of this approach are demonstrated. The principles of AMMС signal formation are explained. The frequency efficiency, energy efficiency, and information efficiency of such signals are theoretically calculated. Different types of digital modulation are compared, the data being presented as a table, and a conclusion is made about a possible practical implementation of the modulator for AMMC signal formation. Structural and functional diagrams of the modulator for AMMC implementation are proposed. The study formulates basic operating principles of such a device, which are used to propose a design option of the modulator. The paper describes particular aspects of creating the main units of the modulator. The authors investigate the characteristics of such a device, particularly the spectrum of the output signal. The obtained research results allow drawing a conclusion that the device complies with the formulated implementation principles of the declared modulation type. A general conclusion is made that the manufactured modulator is suitable for the AMMC. The device is proposed to be used in modern digital communication systems, such as mobile communication systems.

Волоконно-оптический гироскоп с фазовым информационным сигналом

A review of the methods of obtaining and processing the VOG signal is carried out. A gyroscope with the formation of a phase information signal in an interference loop (at the optical level) is proposed. The analysis of digital phase difference meters is carried out. The advantages of a gyroscope with a phase information signal and digital signal processing are the linearity of the scale factor, an increase in the dynamic range and a reduction in the influence of external factors on the measurement result.

МЕТОД МНОГОМЕРНОЙ ДИНАМИЧЕСКОЙ МАРШРУТИЗАЦИИ В РАДИОСЕТИ

Introduction: The introduction of information technology has accelerated the development of methods to improve communication systems. The aim of the study is to improve the efficiency of the network with batch data transmission. Methods: achieving the goal is carried out in three stages, the first stage is considered the task of expanding the functions of repeaters, the second — the functions of the relay are combined with the functions of the switch, and then considered the possibility of obtaining a super-sumar effect through the system use of the repeater-switch-converter. Results: spatial coding of message delivery tracks through real and virtual repeaters allows you to expand the many routes through which, according to the specified criteria, packages are transferred, in the points of space agreed by subscribers is the formation of packages in enlarged groups, transformation by separation methods and spatial switching to the following switching points. The process of forming a spatial field of relay points and visualization of the separation of routes of radio transmissions was carried out. Practical significance: the formation of multiple signals at the focus points implements transformation processes, and the joint processing of processes at multiple relay points provides a switching through the space, for example, for the coordinate space, the lighting of the area of uncertain reception. Discussion: The implementation of a new set of resource management principles in the delivery of communication creates conditions for a significant increase in the simultaneous use of information technologies in a unit of space, allowing for the implementation of a new approach, which is to combine the processes of separation and cooperation of the means of information exchange into self-organizing systems, to jointly perform an expanded range of tasks.

Synthesis, Characterization and Biological Evaluation of Metal Complexes (Zinc, Iron, Copper, Antimony, and Tin) of Sulphanilamide Derivatives

Due to the emerging problem of antibiotic resistance. Its high time that new medicinal products need to be investigated to tackle this problem. Synthesis and characterization of metal-based Sulfa drugs have gained a lot of attention in past few decades, because of their enhanced therapeutic applications. Current study includes the synthesis and characterization of a sulphanilamide ligand and its metal complexes by reacting Sulphanilamide and P-toluene sulphonyl chloride and then reacting them with ten different metals like zinc, copper, iron, tin and antimony to make their metal complexes and to prepare new metallodrugs with improved biological activities. Biological activity of the compounds were determined by screening ligand and metal complexes for antibacterial, antifungal and antioxidant potential. All complexes were successfully made and are found to have significant antibacterial, antifungal and antioxidant activity. In Infrared Spectroscopes the absence of primary stretch from the ligand in metal complexes confirms the attachment of metal. The appearance of new IR band which were absent in ligand spectra are assigned as metal bonds with NH and support the formation of metal complexes. In the 1 H NMR and 13 C NMR spectra of all complexes, the change in the appearance of peaks and formation of proton signals for the groups attached to metals confirmed the formation of complexes. In the spectra of 13 C NMR of all complexes the peaks representing specific carbon confirm the formation of complexes. The groups attached with added metal complexes also showed their peaks which are in agreement with the proposed structures. The results of biological assays showed improved antibacterial, antifungal and antioxidant activity in all metal complexes than the ligand.

Algorithmic support of low-altitude aircraft flight based on the hazard analysis of the flight situation

Low-altitude flight of an aircraft is an effective, but at the same time, a very complex tactical technique, during which the crew does not always have the opportunity to timely recognize the occurrence of an abnormal case, determine the way out of it and counteract an aviation accident development. Despite many advantages of the automatic mode of low-altitude flight performing, its practical implementation is associated with a number of features and disadvantages, which determined the preference for the manual mode of low-altitude flight control. These are the presence of telltale factors, limited ability of performing flights at night and in difficult weather conditions, insufficient reliability etc. The considered features determined the relevance of the of low-altitude flight safety ensuring problem in relation to the manual control mode. As a result of an experimental study of the low-altitude flight performing process in a manual control mode, it was found that when performing manually-controlled low-altitude flight, a hazard assessment of the flight situation becomes pivotal. However the crew being under such conditions is not always able to correctly assess the flight situation hazard due to a combination of objective reasons. The current state of the adaptive and on-board flight safety systems theory makes it possible to increase the safety of the manuallycontrolled low-altitude flight by using adaptive control algorithms based on the flight situation hazard assessment. To solve this problem an adaptive control algorithm is proposed that ensures the formation of a security corridor in the longitudinal control channel, where the upper limit is determined by the critical value of the aircraft detection hazard, and the lower limit is determined by the critical value of the error in maintaining a given flight altitude. For a continuous assessment of the flight situation hazard and the timely formation of control signals the complex information about the current true flight altitude and the foreground is needed. Taking into account the peculiarities of low-altitude flight a digital terrain map containing data on natural and artificial obstacles along the flight route is a more rational source of information, that will make it possible to predict the development of the flight situation hazard. The above reasoning makes it possible to form an aircraft low-altitude flight adaptive control algorithm. A distinctive feature of the proposed algorithm is the implementation of a combined control variety where the pilot is provided with ample manual control opportunities within the security corridor, and the automatic flight control system is assigned the role of a safety subsystem that ensures control and timely return of the flight situation to normal flight conditions. The presented algorithm will allow to increase the crew logical-analytical activity information support during continuous analysis of the existing flight situation due to the formation of protective control actions based on the current flight situation hazard analysis.

Влияние механических напряжений на поведение лазерных ультразвуковых сигналов вблизи отверстия в керамике нитрида кремния

An experimental study of the behavior of laser ultrasonic signals near a hole in a plate from dielectric silicon nitride ceramics under the action of external compressive stresses is carried out. A fundamental discrepancy between the results obtained and similar results obtained by us earlier for metals and a quantitative discrepancy with the predicted thermodynamic model of the formation of thermoelastic signals from stressed materials is shown. An explanation of the observed discrepancies is proposed using the model of thermal excitation of lattice defect states that we proposed earlier.

Comparative analysis of the equipment for the formation of navigation radio signals of the GLONASS system and features of group navigation radio signals

In this paper comparative analysis of methods for forming navigation radio signals of the GLONASS system at each stage is presented. This analysis gives a clear picture of the evolution of the methods for forming navigation radio signals, and provides insights into their advantages and disadvantages. Special attention is paid to group navigation signals of the GLONASS system, namely the effective power amplification of the group navigation radiosignal.