Cardiac biopotentials influence on central nervous system functioning: first steps in hypothesis verification

The research goal is to verify the hypothesis on influence of cardiac biopotentials on central nervous system. Materials: 20 healthy individuals aged 18-26 years old have been participated in the investigations. Two groups composed of 10 patients each have been formed. Double increase in heart biopotentials by means of artificial impulse insertion between natural cardiac contractions has been modeled. Artificial impulses have been similar to unaffected ones, produced in a normal heart work. Additional impulses have been generated using external pacemaker and have been linked up with electrodes on the chest. They have been synchronized with the heart rhythm and located in-between R waves. The duration of those impulses has been fully matched to ventricular complex. Their amplitude has been adjusted individually depending on the height of R wave. Nervous system mobility has been used as the indicator reflecting the central nervous system functioning. Degree of mobility has been defined on the basis of tapping test results. The test has been repeated at specific intervals. Groups have been exposed to two adverse testing modes. Additional impulses have been conducted to the patients of group I within an hour over a period of the first and the third 15-minute intervals and to the patients of group II over a period of the second and the fourth 15-minute intervals. In the middle and in the end of each time interval tapping test has been carried out. After preliminary analysis two other modes of stimulation have been tested. The stimulation has been performed within the 40-minute course: over a period of the first 20-minute interval and vice versa. Results: Detailed evaluation has revealed that short-time increase of nervous processes has been checked in combination with decrease in their stability. Conclusion: The data obtained have shown that there is possible influence on central nervous system functioning. The article ends with prospects of further investigation

Asymptotic self-similar solutions with a characteristic time-scale

For a wide variety of initial and boundary conditions, adiabatic one dimensional flows of an ideal gas approach self-similar behavior when the characteristic length scale over which the flow takes place, $R$, diverges or tends to zero. It is commonly assumed that self-similarity is approached since in the $R\to\infty(0)$ limit the flow becomes independent of any characteristic length or time scales. In this case the flow fields $f(r,t)$ must be of the form $f(r,t)=t^{\alpha_f}F(r/R)$ with $R\propto(\pm t)^\alpha$. We show that requiring the asymptotic flow to be independent only of characteristic length scales imply a more general form of self-similar solutions, $f(r,t)=R^{\delta_f}F(r/R)$ with $\dot{R}\propto R^\delta$, which includes the exponential ($\delta=1$) solutions, $R\propto e^{t/\tau}$. We demonstrate that the latter, less restrictive, requirement is the physically relevant one by showing that the asymptotic behavior of accelerating blast-waves, driven by the release of energy at the center of a cold gas sphere of initial density $\rho\propto r^{-\omega}$, changes its character at large $\omega$: The flow is described by $0\le\delta<1$, $R\propto t^{1/(1-\delta)}$, solutions for $\omega1$ solutions with $R\propto (-t)^{1/(\delta-1)}$ diverging at finite time ($t=0$) for $\omega>\omega_c$, and by exponential solutions for $\omega=\omega_c$ ($\omega_c$ depends on the adiabatic index of the gas, $\omega_c\sim8$ for $4/3<\gamma<5/3$). The properties of the new solutions obtained here for $\omega\ge\omega_c$ are analyzed, and self-similar solutions describing the $t>0$ behavior for $\omega>\omega_c$ are also derived.Comment: Minor corrections, Accepted to Ap

Embodied learning at a distance: From sensory-motor experience to constructing and understanding a sine graph

Educational technologies develop quickly. Which functions of face-to-face education can be substituted by technology for distance learning? One of the risks of online education is the lack of embodied interactions. We investigate what embodied interactive technologies might offer for teaching trigonometry when learning at a distance. In a multiple case study, we analyze the potential of embodied action-based design for fostering conceptual understanding of a sine graph. It appears that independent learning with tablet-based activities leads to acquiring new sensory-motor coordinations. Some students include these new embodied experiences into mathematical discourse and trigonometry problem solving themselves, while others still need some support from a teacher. However, distantly acquired embodied experiences can be easily recalled in a few days after learning and serve well as a substrate for further conceptualization and problem-solving. The results speak for a clear contribution that embodied design might provide for grounding conceptual understanding in distance learning. However, we expect embodied design to be particularly helpful in a blended learning format

Multiscale Transforms for Signals on Simplicial Complexes

Our previous multiscale graph basis dictionaries/graph signal transforms -- Generalized Haar-Walsh Transform (GHWT); Hierarchical Graph Laplacian Eigen Transform (HGLET); Natural Graph Wavelet Packets (NGWPs); and their relatives -- were developed for analyzing data recorded on nodes of a given graph. In this article, we propose their generalization for analyzing data recorded on edges, faces (i.e., triangles), or more generally $\kappa$-dimensional simplices of a simplicial complex (e.g., a triangle mesh of a manifold). The key idea is to use the Hodge Laplacians and their variants for hierarchical partitioning of a set of $\kappa$-dimensional simplices in a given simplicial complex, and then build localized basis functions on these partitioned subsets. We demonstrate their usefulness for data representation on both illustrative synthetic examples and real-world simplicial complexes generated from a co-authorship/citation dataset and an ocean current/flow dataset.Comment: 19 Pages, Comments welcom

Professor Pavel Nikolaevich Nikolaev (to the 130-th anniversary)

The article presents biography of professor P. N. Nikolaev. It reflects his scientific and practical contribution to the development of the most significant directions in Russian medicine including professional training of Health Service specialist