The Mediating Effect of Self-Control on Depression and Tendencies of Eating Disorders in Adolescents

Self-control is very important for the adaptation among adolescents. It is associated with depression and tendencies of eating disorders. This study aimed to investigate the relationship between the two and the mediating role of self-control for adolescents. In total, 1,231 adolescents (11–18 years) participated in this study. Self-control, depression, and tendencies of eating disorders were evaluated using the Dual-Mode of Self-Control Scale (DMSC-S), 11-item Kutcher Adolescent Depression Scale (KADS-11), and Eating Attitudes Test (EAT-26). The correlations among these factors were analyzed using mediating effect models. Girls had higher scores on the both subscales (impulse system and control system) of DMSC-S (P < 0.001). Those between 15–18 years had higher scores on impulse system than those between 11–14 years (P < 0.001). A significant mediating effect (12.8%) of the impulse system was observed between depression and tendencies of eating disorders in adolescents.

THE POWER OF NO-LAG TECHNICAL INDICATORS IN ALGORITHMIC TRADING

In the framework of technical analysis for algorithmic trading we introduce an original approach to classical technical indicators. For this, we consider technical indicators as bounded operators: this more abstract, but also more algorithmic view enables us to define in a very simple way the no-lag versions of these tools. Delay in response is indeed a major drawback of many classical technical indicators used in algorithmic trading, which often leads to a wrong information. On the contrary, with the no-lag versions of the indicators that we study here, we get better information that is closer to the instantaneous values of the securities, hence a better expected rate of return of the trading system in which they occur. After having recalled the definitions of weighted and exponential averages as bounded operators, we prove that the lag possesses a fundamental property that is very useful to create no-lag versions of technical indicators. This being done, we apply our results to a basic trading system and test it on the S&P 500 index, in order to compare the classical Elder’s impulse system with its no-lag version and the so-called Nyquist-Elder’s impulse system: we observe on this example that the no-lag versions of indicators lead to much more profitable systems. More precisely, the Nyquist-Elder’s impulse system is much better than the Elder’s impulse system without lag, which is itself better than the classical impulse system: the information given by Nyquist-Elder’s impulse system is indeed closer to the instantaneous value of the S&P 500 index since it has less delay than the classical impulse system: Nyquist-Elder’s impulse system is even the closest to the instantaneous value among the three ones. We eventually compare the profit/loss of four portfolios (a portfolio that replicates S&P 500 index, and one for every of the three impulse systems) in order to better understand the time dynamics of our three Elder’s impulse systems. As far as we can see, we also notice a lower draw-down for the portfolio associated to the system using the Nyquist-Elder’s impulse system than for the other ones, and this portfolio seems to be more resistant to bearish periods.

Vibration Stability of the Impulse System of the Electric Drive Control

Purpose of reseach is Study of vibration stability of the impulse system of direct current electric drive in order to ensure operating modes with specified dynamic characteristics. Methods. The stability analysis of periodic solutions of differential equations with discontinuous right-hand side is reduced to the problem of studying local stability of fixed map points. Results. The analysis of stability is carried out depending on the supply voltage of the electric drive and the gain of the correcting link in the feedback circuit. It is revealed that the boundary of the stability region on the plane of the variable parameters has a pronounced extremum in the form of a maximum at the bifurcation point of codimension two, also called the resonance point 1: 2. On one side of this point, the stability region is bounded by the NeimarkSacker bifurcation line, and on the other, by the period-doubling bifurcation line. This means that with a change in the parameters, the radius of the stability region first increases, reaching a maximum at the resonance point 1: 2, and then decreases. This important conclusion can be used in optimization calculations. Conclusion. The analysis of the vibration stability of the impulse system of direct current electric drive, the behavior of which is described by differential equations of the discontinuous right-hand side, is carried out. The problem of finding periodic solutions to differential equations is reduced to the problem of finding fixed points of the map. The fixed points of the map satisfy a system of nonlinear equations, which was solved numerically by the NewtonRaphson method. The stability of periodic solutions of differential equations corresponds to the stability of fixed points of the corresponding map. The studies were carried out with variation of the gain in the feedback circuit and the supply voltage. It is revealed that the loss of a fixed point occurs through the supercritical Neimark-Sacker bifurcation, when the complex-conjugate pair of multipliers leaves the unit circle when the parameters change. However, with an increase in the supply voltage, the Neimark-Saker bifurcation boundary passes into the perioddoubling bifurcation boundary at the 1: 2 resonance point.

Model identification of a hydropulse system with periodic external action

Functioning of hydro-impulse systems, usually involves the existence of some periodic external action, that determines the type of model. In this case they use, as a mathematical model, non-autonomous system of ordinary differential equations. Sometimes external action information is incomplete or absent. This may complicate the modeling task. For example, in the operation of hydro-pulse systems, not only their constant parameters but also the type of external action may be unknown. This study is devoted to the identification of a model of a hydro-impulse system in the form of a non-autonomous system of ordinary differential equations. The general form of the equations and one of the observed variables of the system are known, while the constant coefficients of the equations are unknown. We consider the identification problem when we know almost nothing about external action. Namely, we suppose that only its periodic character is known, and its form, period, and phase shift are unknown. Such a problem is obviously more complicated than a typical one, when the external action and the output are completely known, and only the constant coefficients of the equations of the system are to be found. As it is known, for some parameter sets and periodic external action, the observed variable may not be periodic, which makes it impossible to determine the period and other parameters of external oscillations in a simple way. Therefore, identification of the external action is also part of the formulated task. To solve this problem we use algorithm that allows to determine the model parameters with utilizing a known observed variable and incomplete information on the external action. Moreover, the observed variable can be either regular or chaotic.