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A study has been made of the flow of a non-Newtonian polymer medium in a plane channel and of heat transfer in it with boundary conditions of the first kind for small Reynolds numbers and a large Péclet number with the Ellis rheological model with a viscosity dependent on the temperature, pressure, and degree of chemical conversion of the medium. Consideration was given to the flow of a high-viscosity medium with chemical reactions leading to an abrupt increase in its viscosity for whose mathematical description the authors used a model that included the kinetic chemical-reaction equation and the energy equation with a dissipative term. Significant influence of various factors on the formation and rate of growth of the solidified wall layer in such flow has been shown. The problem has been solved numerically by the finite-diff erence method according to the iterative scheme.

It is shown that any incomplete system of reproducing kernels in a model subspace K θ = H 2 ⊖ θH 2 of the Hardy space H 2 can be complemented to a complete and minimal system of reproducing kernels. Thus, any nonuniqueness set for K θ can be complemented to a minimal uniqueness set.

Understanding what, how, and how often apex predators hunt is important due to their disproportionately large effects on ecosystems. In Lake Baikal with rich endemic fauna, Baikal seals appear to eat, in addition to fishes, a tiny (<0.1 g) endemic amphipod Macrohectopus branickii (the world’s only freshwater planktonic species). Yet, its importance as prey to seals is unclear. Globally, amphipods are rarely targeted by single-prey feeding (i.e., nonfilter-feeding) mammals, presumably due to their small size. If M. branickii is energetically important prey, Baikal seals would exhibit exceptionally high foraging rates, potentially with behavioral and morphological specializations. Here, we used animal-borne accelerometers and video cameras to record Baikal seal foraging behavior. Unlike the prevailing view that they predominantly eat fishes, they also hunted M. branickii at the highest rates (mean, 57 individuals per dive) ever recorded for single-prey feeding aquatic mammals, leading to thousands of catches per day. These rates were achieved by gradual changes in dive depth following the diel vertical migration of M. branickii swarms. Examining museum specimens revealed that Baikal seals have the most specialized comb-like postcanine teeth in the subfamily Phocinae, allowing them to expel water while retaining prey during high-speed foraging. Our findings show unique mammal–amphipod interactions in an ancient lake, demonstrating that organisms even smaller than krill can be important prey for single-prey feeding aquatic mammals if the environment and predators’ adaptations allow high foraging rates. Further, our finding that Baikal seals directly eat macroplankton may explain why they are so abundant in this ultraoligotrophic lake.

New subglacial BEDMACHINE model shows the presence of a large number of narrow and deep bedrock depressions in various regions of Antarctica with depths up to 3500 m below sea level (Denman Depression). Nothing similar is observed for other continents – on land, depressions usually do not exceed several hundred meters in depth, and the deepest continental rift depressions filled with water, such as Baikal or Tanganyika, also have a significantly shallower depth. Since sedimentation under the ice sheet is practically impossible, the authors suggest that the formation of these deep subglacial uncompensated troughs is associated with the activation of rifting already after the glaciation of Antarctica. At the same time, when the rift structure approaches the coast of the continent, its subglacial relief sharply flattens out, which indicates sedimentation in the transitional area during periods of ice melting and subsequent marine regressions-transgressions. Negative gravity anomalies in the free air of the order of –100 mGal for many subglacial depressions testify in favor of their rift nature. Rifting involves an increased heat flow, which can lead to melting of the glacier base and promote their accelerated sliding from the bedrock into the ocean. This explains the confinement of the most rapidly moving glaciers in Antarctica to the areas of rift depressions. Accelerated flow of glaciers into the ocean creates a potential threat of rising sea levels. The geodynamic mechanism responsible for the Cenozoic activation of the Antarctic rift zones is associated with the action of local upper mantle plumes under Antarctica. The existence of a subglacial volcanic province in the area of the Gaussberg volcano in East Antarctica is assumed.

This paper investigates the mechanical properties of oriented polyvinyl chloride (PVC) nanofiber mats, which, were obtained by electrospinning a PVC solution. PVC was dissolved in a solvent mixture of tetrahydrofuran/dimethylformamide. Electrospinning parameters used in our work were, voltage 20 kV; flow rate 0.5 mL/h; the distance between the syringe tip and collector was 15 cm. The rotating speed of the drum collector was varied from 500 to 2500 rpm with a range of 500 rpm. Nanofiber mats were characterized by scanning electron microscope, thermogravimetric analysis, differential scanning calorimetry methods. The mechanical properties of PVC nanofiber mats, such as tensile strength, Young’s modulus, thermal degradation, and glass transition temperature were also analyzed. It was shown that, by increasing the collector’s rotation speed from 0 (flat plate collector) to 2500 rpm (drum collector), the average diameter of PVC nanofibers decreased from 313 ± 52 to 229 ± 47 nm. At the same time, it was observed that the mechanical properties of the resulting nanofiber mats were improved: tensile strength increased from 2.2 ± 0.2 MPa to 9.1 ± 0.3 MPa, Young’s modulus from 53 ± 14 to 308 ± 19 MPa. Thermogravimetric analysis measurements showed that there was no difference in the process of thermal degradation of nanofiber mats and PVC powders. On the other hand, the glass transition temperature of nanofiber mats and powders did show different values, such values were 77.5 °C and 83.2 °C, respectively.

The article presents the results of the calculation of dynamic multipliers produced by an increase in public spending in various industries of the Russian economy. The calculations are based on a dynamic input–output model for 72 industries with distributed construction lags. Dynamic multipliers are defined as the ratio of the increase in the gross output of the national economy in the forecast version with an increase in investment or noninvestment spending relative to its value in the version without such an increase to the increase in the corresponding costs. The calculations are performed for the period 2023–2032. It is shown that for investment spending the dynamic multipliers are positive and 2.5–3 times higher than the corresponding static ones for all industries. For noninvestment and total spending, the multipliers are positive for most industries and negative for some. It is also shown that dynamic investment multipliers increase every year, but the growth rate of that increase slows down. The structure of dynamic multiplier effects is considered with a breakdown by sections of the economy corresponding to industrial consumption and to household final consumption. Calculation of dynamic multipliers enables assessment of not only short-term effects of investments, but also accumulated effects of deployment of fixed assets over several years.

As the number of space objects (SO) increases, collision avoidance problem in the rendezvous tasks or reconstellation of satellites with SO has been paid more attention, and the dangerous area of a possible collision should be derived. In this paper, a maneuvering method is proposed for avoiding collision with a space debris object in the phasing orbit of the initial optimal solution. Accordingly, based on the plane of eccentricity vector components, relevant dangerous area which is bounded by two parallel lines is formulated. The axises of eccentricity vector system pass through the end of eccentricity vector of phasing orbit in the optimal solution, and orientation of axis depends on the latitude argument where a collision will occur. The dangerous area is represented especially with the graphical dialogue, and it allows to find a compromise between the SO avoiding and the fuel consumption reduction. The proposed method to solve the collision avoidance problem provides simplicity to calculate rendezvous maneuvers, and possibility to avoid collisions from several collisions or from \"slow\" collisions in a phasing orbit, when the protected spacecra and the object fly dangerously close to each other for a long period.

A geodynamic model of the modern Earth was constructed based on the SMEAN 2 global seismic tomography model. Considering the distribution of mantle temperature anomalies in this model, the numerical simulation of a three-dimensional flow of a viscous mantle was carried out taking into account the dependence of the viscosity on temperature and depth in the spherical Earth. The Stokes equation was solved by the finite element method using the CitcomS code. The obtained data on the distribution of the temperature anomalies, dynamic topography, and velocity field in the mantle were used to analyze structural features and geodynamics in the West Antarctic region, as well as the anomalous acceleration of glacier movement and destruction in this area. In particular, the existence and current activity of the West Antarctic Rift System including one of the largest volcanic provinces on the Earth were explained. This explanation was consistent with the measurement data on increased heat flow on the surface. The increased heat flow and volcanic activity in this region lead to instability and accelerated runoff of the West Antarctic ice sheets into the ocean, thus posing the potential threat of a substantial rise in the global sea level.

AbstractInstantaneous velocity of three-dimensional flows in the Earth’s mantle is calculated using the Stokes equation and non-Newtonian rheology, based on the SMEAN 2 global seismic tomography model. This model automatically takes into account the fundamental forces acting in the mantle and on the Earth’s surface. The constructed 3D model of mantle flows describes in detail horizontal movements of the Earth’s surface observed using the satellite geodesy and provides a quantitative basis for interpreting the features of regional geological processes. The constructed spherical 3D model of modern global geodynamics is a quantitative generalization of the plate tectonics theory for the current Earth’s development stage.

Background Understanding how predatory animals efficiently locate prey with limited knowledge of its location is challenging. Optimal foraging theory suggests that animals improve their food intake through experience-based adjustments of search patterns. For example, animals feeding on clustered prey may repeatedly search successful areas and move farther away when unsuccessful (the ‘win-stay, lose-shift’ strategy). A related concept, area-restricted search, predicts that animals initially search broadly and then switch to a more localized, tortuous search upon finding clustered prey. However, few studies have empirically supported these predictions for large aquatic predators due to difficulties in recording their foraging success on known prey species. Methods We used biologging techniques to record the fine-scale foraging behaviour of Baikal seals in Lake Baikal, which hunt tiny, clustered, planktonic amphipods at high rates. We reconstructed their three-dimensional movement paths during dives and estimated the timing of prey capture events based on video-validated body acceleration data. Results Seals moved shorter horizontal distances and exhibited greater directional changes after more successful dives, supporting the ‘win-stay, lose-shift’ strategy. Consistent with area-restricted search, successful foraging dives led to decreased speed and increased tortuosity in the horizontal plane. Conclusions These findings suggest that experience-based behavioural adjustments at a dive-to-dive scale are crucial for Baikal seals—and possibly other large aquatic predators—to maintain high foraging rates. Furthermore, they illustrate how an exceptionally high predator-prey body mass ratio (> 500,000) for a single-prey-feeding (non-filter-feeding) predator is maintained in the unique Lake Baikal ecosystem.