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Background and Objectives: The Josephson effect is widely used for both generating and receiving very high frequency signals. The approaches and methods of nonlinear dynamics are commonly used: construction of phase portraits, bifurcation analysis, Kuramoto model approach, etc. Usually large arrays of identical junctions are considered. However, the non-identity of junctions leads to new and interesting effects. A very popular model is a chain of junctions connected via an RLC circuit. In this case, two types of non-identity are possible – in terms of critical currents IN through the junctions and in terms of the value rN of junction resistances. An increase in the number of junctions from two to three leads to the possibility of quasiperiodic dynamics with invariant tori of dimensions both two and three and to a complex structure of the parameter space. Materials and Methods: In this paper, we will mainly consider three junctions that are not identical in terms of resistance. As the main research tool, we will use the method of construction of Lyapunov exponent charts. Within the framework of this method, the type of dynamics of the system is determined by the signature of the spectrum of Lyapunov exponents. The parameter plane is scanned and the types of modes are identified at each point. The method is effective in that it allows one to study all types of possible regimes and fine details of the parameter space arrangement. Results: For the analysis of the dynamics of non-identical Josephson junctions, the method of Lyapunov exponent charts is effective. With its help, the regions of periodic regimes, regimes of two-frequency and three-frequency quasiperiodicity, chaos have been revealed. As a rule, the regions of two-frequency quasiperiodicity have the form of bands of different widths immersed in the region of three-frequency quasiperiodicity, which form the structure of the Arnold’s resonant web. Conclusion: The boundaries of the regions of two-frequency quasiperiodicity are the lines of saddle-node bifurcations of invariant tori. As the area of chaos increases, the Arnold’s resonant web can collapse. Changing the type of external circuit coupling the junctions does not fundamentally affect the dynamics of the system.

Background and Objectives: Quasi-periodic oscillations are widespread in nature and technology. In the phase space, quasi-periodic oscillations with a different number of incommensurable frequencies correspond to invariant tori of different dimensions. Multiparametric analysis of high-dimensional systems is quite difficult. The way out of this situation can be the transition from systems with continuous time to discrete maps. Materials and Methods: In the paper we use a discretization method for the transition from a continuous-time system (two coupled quasi-periodic generators) to a new high-dimensional map. The time derivatives are replaced by finite differences. There is a new additional parameter corresponding to the discretization step, with the variation of which the system can demonstrate new interesting properties. Results: A new high-dimensional map has been obtained by the discretization method of differential equation system of coupled quasi-periodic generators. For this map, charts of Lyapunov exponents have been constructed in the plane of the frequency detuning of generators and the coupling magnitude. The existence of invariant tori of different dimensions has been demonstrated. Graphs of Lyapunov exponents and Fourier spectra have been presented. The evolution of maps with an increase of the discretization parameter has been investigated, the destruction of high-dimensional tori has been demonstrated. The influence of noise of different intensity has been studied. Conclusion: The two-parameter Lyapunov analysis of the new high-dimensional map made it possible to identify regions of invariant tori of different dimensions, up to fivefrequency ones. The map demonstrates Fourier spectra characteristic of quasi-periodicity of increasing dimension. Quasi-periodic bifurcations of invariant tori and an Arnold resonance web based on invariant tori of different dimensions have been observed. With the growth of the discretization parameter, the destruction of high-dimensional tori occurs. An increase in the discretization parameter leads to the destruction of high-dimensional tori with an increase in the noise intensity.

Background and Objectives: The basic model of study is the simplest three - dimensional map with two-frequency and three-frequency quasiperiodicity at adding of noise. The main objective is to examine the effect of noise on the quasiperiodic Hopf bifurcation of the 3-torus birth. Materials and Methods: To study the torus map in the presence of noise we use such numerical methods as computing of Lyapunov exponents, calculation of Fourier spectra, drawing of attractor portraits. Results: Quasi-periodic bifurcations under the influence of noise occupy certain intervals in the parameter, but their main classification features (equality or not of the corresponding Lyapunov exponents) are preserved at the qualitative level. Conclusion: We considered the effect of noise on the simplest system with two- and three-frequency quasiperiodicity. The three-frequency quasiperiodicity is preserved at certain noise amplitudes, but then turns into a two-frequency one. In the Fourier spectra, this process develops according to the scenario of "blurring" the noise components of the corresponding spectral components.

Background and Objectives: Chaotic behavior is one of the fundamental properties of nonlinear dynamical systems, including maps. Chaos can be most easily and reliably diagnosed using the largest Lyapunov exponent, which will be positive for the chaotic mode. Unlike flow dynamical systems, the presence of zero Lyapunov exponent in the spectrum is not an obligatory condition for maps. The zero exponent in the spectrum of a map will indicate the possibility of embedding such a map in a flow. In the framework the present paper, using as an example a three-dimensional discrete Lorenz-84 model, it is shown that there can appear chaotic attractors whose Lyapunov exponent spectrum contains one positive, one zero, and one negative exponents. Such a specific attractor represents the production of a two-dimensional torus and the Hénon attractor and was called the Quasi-periodic Hénon attractor. A scenario of development of such kind behavior is an open problem. Materials and Methods: The discrete Lorenz-84 oscillator obtained by discretizing the three-dimensional flow Lorenz-84 model is considered as an object of the present research. The dynamics of the map is studied numerically. The main analysis is carried out using the charts of dynamical regimes based on the calculation of Lyapunov exponents. Lyapunov exponents were calculated by the Benettin method with Gramm-Schmidt orthogonalization. Results: The scenario of occurrence of the Quasi-periodic Hénon attractor via a cascade of invariant curve doubling bifurcations is described. Conclusion: We study the discrete Lorenz-84 oscillator, which is a three-dimensional map (three-dimensional diffeomorphism). In the map the possibility of implementing a steady state of equilibrium, an invariant curve, a torus-attractor, and chaos with zero Lyapunov exponent in the spectrum was shown. It is also demonstrated that the chaotic mode with zero Lyapunov exponent, the Quasi-periodic Hénon attractor, can appear as a result of a cascade of doubling bifurcations of the invariant curve. Typical structures on the parameter plane, such as CrossRoad-Area, Spring-Area, whose base mode is an invariant curve, are illustrated. These structures and chaotic oscillations can arise on the basis of various invariant curves.

Our purpose was to carry out a comparative phytochemical analysis of fruits (both fresh and stored for 1 month) of two local apple varieties of the Republic of Tajikistan. Assays were carried out to quantify total phenolic compounds, flavonols, catechins, tannins, phenolcarboxylic acids, pectins, and protopectins by UV spectrometry and ascorbic acid by titration. The profile and levels of phenolic compounds were investigated by high-performance liquid chromatography. Antiradical activity was quantitated by means of free radical DPPH (2,2-diphenyl-1-picrylhydrazyl). In fresh fruits, total levels of tannins (19 mg/g) and phenolcarboxylic acids (15 mg/g) (including chlorogenic acid: 451 μg/g) and of a flavonol (quercetin: 26 μg/g) and two catechins [epigallocatechin (173 μg/g) and L-epicatechin (50 µg/g)] were shown to be higher in the Surkhseb apple variety than in the Kosimsarkori variety. The antioxidant activity of water–ethanol extracts from Surkhseb apples (20 mg/mL) was also higher in comparison with Kosimsarkori apples. In the latter, concentrations of other detected biologically active substances, such as flavonols (0.78 mg/g), ascorbic acid (65 mg/100 g), and pectins (37 mg/g), were found to be higher, suggesting that the fruits of this apple variety have biological effects other than antioxidant, potentially anti-inflammatory, or antidiabetic. Further phytochemical and pharmacological studies on Kosimsarkori fruits may identify these other potential biological effects that may be useful in the prevention of disease. Fruits of the analyzed apple varieties should preferably be consumed fresh because after the apples were stored in the refrigerator for 1 month, indicators of antioxidant activity (22 mg/g in Surkhseb apples) and levels of almost all biologically active substances (tota) levels of tannins (14 mg/g), phenolcarboxylic acids (9 mg/g) (including chlorogenic acid: 250 μg/g) and catechin L-epicatechin (30 µg/g) in Surkhseb apples decreased. This study highlights the importance of conserving local, unique varieties of major worldwide crop plants because they may unearth novel combinations of compounds beneficial to humanity. [ABSTRACT FROM AUTHOR]

This article examines the role of the religious and tribal factors in the genesis, development and expansion of the Houthi movement in Yemen. The relevance of this work stems from the transformation of the Ansarullah movement into the driver of not only domestic policy in Yemen but also of regional policy and the regional security situation. The article contains: a scrutiny of Zaydism as one of the leading religions in Yemen and its connection with the Houthi movement; the genesis of the Ansarullah movement and how it became dominant in Northern Yemen; and interrelations of this movement with the Yemeni tribes. The author of the article stipulates that from a religious point of view the Houthi movement reflects the teaching of traditional Zaydism and has its roots in Yemeni history, especially in the al-Mutawakkil Imamate. The article contains an analysis as to how the Houthis succeeded in neutralizing or exploiting the tribes of Yemen, taking into account that the tribal factor was a driver of political instability in the country. The author explains, in part, the success of the Houthis and their domination in conditions of war and conflicts (wars of Saada and the war against the Arabian coalition). [ABSTRACT FROM AUTHOR]

Fabry disease is a lysosomal storage disorder caused by a significant decrease in the activity or absence of the enzyme α-galactosidase A. The diagnostics of Fabry disease during newborn screening are reasonable, due to the availability of enzyme replacement therapy. This paper presents an electrochemical method using complementary metal-oxide semiconductor (CMOS)-compatible ion-sensitive field effect transistors (ISFETs) with hafnium oxide-sensitive surfaces for the detection of α-galactosidase A activity in dried blood spot extracts. The capability of ISFETs to detect the reaction catalyzed by α-galactosidase A was demonstrated. The buffer composition was optimized to provide suitable conditions for both enzyme and ISFET performance. The use of ISFET structures as sensor elements allowed for the label-free detection of enzymatic reactions with melibiose, a natural substrate of α-galactosidase A, instead of a synthetic fluorogenic one. ISFET chips were packaged with printed circuit boards and microfluidic reaction chambers to enable long-term signal measurement using a custom device. The packaged sensors were demonstrated to discriminate between normal and inhibited GLA activity in dried blood spots extracts. The described method offers a promising solution for increasing the widespread distribution of newborn screening of Fabry disease. [ABSTRACT FROM AUTHOR]

Biosensors based on ion-sensitive field effect transistors (ISFETs) combined with aptamers offer a promising and convenient solution for point-of-care testing applications due to the ability for fast and label-free detection of a wide range of biomarkers. Mobile and easy-to-use readout devices for the ISFET aptasensors would contribute to further development of the field. In this paper, the development of a portable PC-controlled device for detecting aptamer-target interactions using ISFETs is described. The device assembly allows selective modification of individual ISFETs with different oligonucleotides. Ta2O5-gated ISFET structures were optimized to minimize trapped charge and capacitive attenuation. Integrated CMOS readout circuits with linear transfer function were used to minimize the distortion of the original ISFET signal. An external analog signal digitizer with constant voltage and superimposed high-frequency sine wave reference voltage capabilities was designed to increase sensitivity when reading ISFET signals. The device performance was demonstrated with the aptamer-driven detection of troponin I in both reference voltage setting modes. The sine wave reference voltage measurement method reduced the level of drift over time and enabled a lowering of the minimum detectable analyte concentration. In this mode (constant voltage 2.4 V and 10 kHz 0.1Vp-p), the device allowed the detection of troponin I with a limit of detection of 3.27 ng/mL. Discrimination of acute myocardial infarction was demonstrated with the developed device. The ISFET device provides a platform for the multiplexed detection of different biomarkers in point-of-care testing. [ABSTRACT FROM AUTHOR]

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Alternation of left and right antimeres of segmental structures, generally known as the glide-reflection symmetry, was found to be unexpectedly widespread in deuterostomes. It occurs in both somatic and visceral organs. Its distribution in echinoderms, acorn worms, cephalochordates, ascidians, hagfishes, and chimaeras might suggest its ancestral nature in deuterostomes. It could have been inherited from Precambrian ancestors. There is a lead of the left segments against their right counterparts in all deuterostomes with glide-reflection symmetry, where the leading side is known. This allows us to presume an inherent left-to-left-side and right-to-right-side homology across all deuterostomes, contradicting a hypothesis of the whole-body dorsoventral inversion in chordates. The features of inversion could be alternatively explained by a transformation of the gastrulation process, which has caused an inversion of dorsoventral polarity in some parts of the body, but did not affect the left–right polarity. It is suggested that this process had involved the animal-vegetal extension of the blastopore along embryonic dorsal side in basal deuterostomes that was followed by the shift of the left–right organizer from the dorsal lip of the blastopore to the anterior tip of archenteron in non-chordate deuterostomes, which has caused roof-to-floor relocation of the notochordal area in their archenteron. [ABSTRACT FROM AUTHOR]

In the article, we studied the continuous problem for multi-agent pathfinding. We show continuity of the path-traversing time functional and the existence of the optimal path for a single agent. Also, we consider game theory interpretation for multi-agent pathfinding with continuous routes as a game with strategies in a Banach space. Finally, we briefly discuss near-optimal routes and connection of heuristics for pathfinding and integral geometry problems. [ABSTRACT FROM AUTHOR]