Kursk State University

This paper considers spaces of delta-subharmonic functions on an open unbounded semiring. We introduce a definition of a delta-subharmonic function of finite $\gamma$-growth on an unbounded semiring in which no restrictions are imposed on the growth function. We obtain criteria for a delta-subharmonic function to belong to this space, which are formulated in terms of the Fourier coefficients of this function. The criteria extend to the semiring the results obtained earlier in a joint work by L.A. Rubel and B.A. Taylor for meromorphic functions on the complex plane and the results of K.G. Malyutin for delta-subharmonic functions on the half-plane.

Minimally invasive endoluminal interventions increasingly rely on magnetic actuation to navigate narrow lumens while limiting wall loads. Here we present a contact-aware control framework for steering a deformable, silicone-based soft microrobot with embedded magnetic particles using an externally positioned permanent magnet. We develop a dynamic model capturing viscous drag, nonlinear frictional loads, and viscoelastic wall contact, and implement a closed-loop architecture that combines vision-based state estimation with model-based force inference while optimizing magnet orientation to regulate the force vector and normal reaction. Performance is evaluated in simulation and on a benchtop testbed across three control modes. In the nominal-case benchmark, force-plus-angle control reduced the root-mean-square tracking error from 4.8 to 2.1 mm (−56%), decreased peak tracking error from 14.6 to 8.0 mm (−45%), lowered the integrated performance index from 4.4 × 10−¹⁰ to 1.6 × 10−¹⁰ (−64%), and attenuated peak normal reaction force from 2.0 × 10−6 to 0.8 × 10−6N (−60%) compared with operation without force regulation. To assess robustness, we further performed a simulation-based Monte Carlo analysis (n = 500 trials per mode) under parametric uncertainty and measurement noise, confirming that the contact-aware modes preserve their performance advantage; non-parametric tests indicated statistically significant inter-mode differences with moderate-to-large effect sizes. A trade-off analysis in the {tracking error, peak normal load} plane showed that, in the explored regime, improved tracking does not inherently require higher peak contact forces. Finally, a first-order shear-thinning surrogate suggested low sensitivity of the relative conclusions to moderate non-Newtonian effects. Overall, the results identify force-aware magnet orientation as a safety-relevant control degree of freedom for endoluminal navigation and provide a transferable control methodology for future magnetic microrobotic platforms.

Chemomechanical gels, which exhibit self-sustained volume oscillations driven by the Belousov-Zhabotinsky reaction, are promising soft materials for the creation of pumps and actuators for microfluidic applications and microrobotics. In this work, we report mechanical characteristics of a microdevice containing a driving part based on a novel self-oscillating gel based on complexes of iron with tridentate $1^{2}, 2^{2}: 2^{6}, 3^{2}$-terpyridine and its derivatives, as well as structural and rheological properties of the latter. The appropriate methods of experimental investigation and data processing are discussed as well.

Magnetic fields can be used to control the process of magnetic fluid dispersion in microfluidics. Here we demonstrate a method for generating magnetic fluid droplets of a given size and shape in a microfluidic chip with a flow-focusing configuration under the influence of a transverse magnetic field. The results of the study show that a magnetic field can have a significant impact on ferrofluid dispersion. At low volumetric flow rates of the continuous phase, magnetic force plays a primary role in ferrofluid dispersion due to disturbances on the magnetic fluid surface. Furthermore, the droplet diameter decreases with increasing magnetic field Dd ∼ H-1/3. At high volumetric flow rates of the continuous phase, shear stress plays a primary role in ferrofluid dispersion. In this case, the droplet diameter depends on the continuous phase velocity according to the law Dd ∼ u-1. The magnetic field and the volumetric flow rate of the continuous phase affect not only the liquid dispersion process but also the coalescence and deformation of droplets. The pressure gradient in the channel and the magnetic field contribute to droplet deformation. The thickness of the deformed droplet decreases with increasing volumetric flow rate according to the law l ∼ Q-1. The non-uniformity of the velocity field distribution over the channel thickness is responsible for droplet coalescence. The magnetic field, on the contrary, prevents droplet coalescence. These findings open up new possibilities for generating soft magnetic robots of a given size and shape.

Aim. To identify the features of the relationship between ethnonational attitudes and indicators of life satisfaction and subjective well-being among university students in the new subjects of the Russian Federation. Methodology. The empirical study was conducted using the “Scale of Ethnonational Attitudes” (O. E. Khukhlaev, I. M. Kuznetsov, N. V. Tkachenko), which provides a multidimensional approach to studying respondents’ generalized attitudes toward nationality and interethnic relations. These attitudes are perceived in Russian public discourse as equivalent to the concept of ethnicity. Additionally, the “Warwick-Edinburgh Scale of Psychological Well-Being” (adapted by S. K. Nartov-Bochaver) was used to assess the level of subjective well-being. Finally, the questionnaire “Life Satisfaction” (N. N. Melnikova) was employed to examine subjective feelings of satisfaction with life. Results. It has been found that among university students from the new subjects of the Russian Federation who are migrants, nationalistic attitudes are associated with lower subjective well-being and lower life satisfaction. On the other hand, patriotic attitudes are linked to higher levels of these indicators. These findings suggest that ethnonational attitudes play a significant role in the subjective well-being of these students, highlighting the importance of considering ethnocultural factors in developing psychological support programs. However, in students from other parts of Russia, these relationships are less prominent or non-existent, indicating a specific role for ethnonational identity in the adaptation process. Research implications. The theoretical significance of the study is to clarify the influence of ethnonational attitudes on the subjective well-being and civic identity of students in the process of their social adaptation. The results obtained will make deeper understanding of the mechanisms possible by which ethnicity and related attitudes can both facilitate and hinder students’ adaptation to new conditions. The practical significance of the research is due to the possibility of using the data obtained for the development and implementation of programs for psychological support and prevention of maladaptation of students in new regions of the Russian Federation. This will make it possible to create more effective strategies for helping students who have difficulty adapting due to ethnonational factors.

In the context of historical and philosophical reflection, the question of the status of the natural world and humanity’s relationship to it has always remained one of the key issues — especially today, when alarming forecasts of global natural cataclysms increasingly warn of potentially catastrophic consequences on a universal scale. The novelty of this research lies in its historical and philosophical analysis of the ethical and axiological interpretation of nature in the Early Middle Ages. The subject of the study is the natural world as an explication of ontological and ethical–axiological meanings in the works of representatives of Greek–Eastern patristics. The object of the study is the origin and meaning of the natural world within the hierarchy of being in patristic philosophy. The study aims to conduct a historical and philosophical analysis of the ontological foundations in the interpretation of nature and the animal world within the context of medieval mental culture. The article presents constitutive positions characterising conceptions of the natural world in Greek–Eastern patristics. It explores the reasons for its creation and interpretations of nature as testimony to God’s will, reflected in the writings of Christian thinkers of the 4th–6th centuries, as well as the significance of the created world in human spiritual experience and as a source of ethical–axiological meanings. The author concludes that the created world as a whole and its individual components, within the theocentric horizon of thought, are central to medieval ontology and reveal the fundamental ethical and axiological principles formed within the mental culture of the Early Middle Ages. A fundamental idea in Greek–Eastern patristics is the transformation of human nature, corrupted by sin, which is to be aided by understanding the meanings established by God in the laws of the universe, including the existence of the animal world. This approach excludes a consumerist attitude towards nature and the utilitarian interpretation of science and scientific knowledge prevalent in the modern era.

Between 2018 and 2023, four new records of sea turtles (Dermochelyidae, Cheloniidae) belonging to three species (Dermochelys coriacea, Chelonia mydas, and Eretmochelys imbricata) were recorded in waters of the Russian Far East. The hawksbill turtle (E. imbricata) is reported from Russia for the first time. This adult female was caught by fishermen in the strait between Kunashir and Shikotan islands. An adult specimen of D. coriacea was captured in nets in the Kunashir Strait of the Sea of Okhotsk near the village of Tretyakovo. Several skeleton fragments of Ch. mydas were found near the Alyokhin Cape of Kunashir Island. The green turtle, Ch. mydas, is recorded from the Kuril Islands for the first time, and it is very likely that specimen belongs to the Pacific subspecies, the black turtle, Ch. m. agassizii. Another species of sea turtle, the olive ridley, Lepidochelys olivacea, is also likely to occur in the southern part of the Far Eastern sea area. The leatherback turtle, D. coriacea, is the only species regularly entering Russia’s waters and has been recorded at least two dozen times in the Sea of Japan, the Sea of Okhotsk, and the Bering Sea, and in the Pacific waters of the Russian economic zone near the southern Kuril Islands. Two other species, the loggerhead, Caretta caretta, and the green turtle, Ch. mydas, have been recorded only a few times. The actual number of sea turtles entering Russia’s waters is higher than the number given in official sources. The tendency for sea turtle records to increase in the temperate and subarctic zones seems to be associated with increased fishing in the region. Bycatch study in temperate and subarctic zones may provide new information on the distribution and biology of sea turtles in the north and also allow for methods for reducing accidental turtle mortality to be developed.

The aim of the research is to broaden the understanding of Dmitry Alexandrovich Khvorostovsky’s oeuvre by addressing the issue of performing early vocal music by Western European composers. The article pays particular attention to the analysis of Baroque musical traditions, as seen in a striking example of the artistic legacy of the era – the aria “Dignare, o Domine” from Handel’s “Dettingen. Te Deum” cantata. The scientific novelty of the research lies in the fact that, for the first time, the aria “Dignare, o Domine” by G. F. Handel, as performed by D. A. Khvorostovsky, embodying the artistic and technical techniques of Baroque music, becomes the object of study. As a result of the research, using this aria as an example, the musical and aesthetic problems of the style and the features of the vocal interpretation of Baroque music by D. A. Khvorostovsky are examined, the performance techniques used are analyzed, and the technical and artistic tasks that this outstanding musician-performer solved when interpreting 18th-century music are summarized.