Peculiarities of Muscle-Tendon Mechanics and Energetics in Elite Athletes in Various Sports

The article presents results of the research on jumping strategies applied by elite athletes in various sport disciplines. Research hypothesis: to perform the same motor task athletes employ different ways of organizing the movement and different features of MTU functioning. The choice of a mechanism to enhance muscle contraction depends on sport discipline, in particular specific features of the sport movement. The study involved members of the Russian national teams in alpine skiing, bobsleighing, mogul skiing and ski jumping. The athletes performed drop jumps from the heights of 0.1, 0.3, and 0.5 m with no arm swing. Experimental data were obtained online from 24 cameras using the Qualisys motion capture system (400 frames per second) and the two force plates AMTI 6000. Data was processed using the OpenSim package. The authors calculated the amount of accumulation and utilization of elastic strain energy and assessed metabolic energy expenditures in MTU. The authors concluded that employment of different strategies of movement organization in drop jumps could be explained by the transfer of motor skills specific to the athlete’s sport discipline. The results of the study may help coaches develop individual training plans for athletes, in particular strength training exercises targeting specific muscle groups

Analysis of microstrip structures by numerical conformal transformations technique

Computer aided microstrip structures modeling has been performed by conformal mapping technique. A new approach to reduce the connectivity order of the original cross-section geometry of the structure is proposed. The multiply connected domain is reduced to simply connected ones by implementation of magnetic slits concept. The microstrip structures analysis is carried out by numerical conformal transformations technique realized in Schwarz–Christoffel toolbox for MATLAB. This technique is applied to the quasi-static analysis of coupled microstrip lines taking into account the conductor thickness. Described approach ensures high numerical efficiency and can be used for accurate analysis of complex microstrip structures

One-year periodization of training loads of Russian and Norwegian elite cross-country skiers

The study intended to compare the training load volume (TrV) distribution of elite Russian (RuXC) and Norwegian (NorXC) cross-country skiers in a one-year macrocycle. Daily TrV of 11 RuXC skiers averaged for the period 2014/15–2017/18. The NorXC skiers’ TrV obtained from the study by Sandbakk (2017). RuXC skiers had a lower volume of low-intensity (LIT, below aerobic threshold) and high-intensity (HIT, above anaerobic threshold) endurance training. They used a “pyramidal” model of intensity ratio during the entire macrocycle and did not decrease the volume of moderate-intensity (MIT) endurance training in competition periods (CPs). Conversely, NorXC skiers followed the “pyramidal” model of intensity in the preparation period (PP) but the “polarized” model in CP, significantly reducing the volume of MIT and increasing that of HIT. RuXC skiers increased TrVs more rapidly at the beginning of PPs, achieving TrV peak in June, and then gradually decreased them by March. NorXC skiers increased TrVs gradually by July and then maintained this approximate volume until November. RuXC skiers had peak volumes of LIT and strength training simultaneously in June; NorXC skiers engaged in large amounts of strength training in May and June until reaching maximum endurance loads. RuXC skiers had two “blocks” of strength training; NorXC skiers had three. A comparative analysis of the TrV distributions among the RuXC and NorXC skiers revealed significant similarity. Therefore, they can consider as models of the modern annual periodization of training loads for this kind of sport

Luminescence in glasses doped with Ag nanoclusters

Ag nanoclusters have recently attracted a great interest of researchers due to a large number of possible applications as phosphors for white light generation or solar spectrum down-conversion, biosensors, catalysts and parts of different nanoelectronic devices. Ag nanoclusters (or Ag molecules) consist of two or more Ag atoms/ ions bonded to each other and, probably, to some other atoms/ ions if they are embedded into a host. Subsequently, they demonstrate significantly different optical and electronic properties compared to bulk Ag particles, such as discrete energy level diagram, photoluminescence with high quantum yield, absence of plasmon band and high chemical reactivity. The optical properties of Ag nanoclusters are highly sensitive to the site in the host, the number of Ag atoms, the total charge and the shape of Ag nanocluster. As Ag nanoclusters exhibit high chemical reactivity they need to be sealed into a host for some particular applications. Oxyfluoride glass is a good candidate for Ag nanoclusters host as this glass can be easily prepared by conventional melt-quenching method. It furthermore allows dissolving of large amounts of various co-dopants (Ag nanoclusters and Rare-Earths ions), is transparent and non-luminescent in a very wide range of wavelengths from UV to Infra-red. The development of particular applications based on photoluminescence of Ag doped oxyfluoride glasses requires the detailed understanding of the interaction between light and Ag nanoclusters in this glass host. Photoluminescence Spectroscopy is a very powerful tool for studying Ag nanoclusters able to provide us such kind of information. Photoluminescence excitation and emission spectroscopy can provide us information about absorption and emission bands of luminescent centers. Photoluminescence kinetics gives furthermore information about the approximate number of the luminescent centers, energy transfer between the luminescent centers and photoluminescent lifetimes of the luminescent centers. Modern Quantum Chemistry Methods (Density Functional Theory and Ab Initio Methods) provide an opportunity to calculate absorptionbands, energy level diagrams and lifetimes of the luminescent centers. Therefore, we can get insight into the interaction between light and hosted Ag nanoclusters through comparison between experimental and theoretical results obtained by Photoluminescence Spectroscopy and Quantum Chemistry calculations. The main aim of this PhD thesis is to study and explain pico-, nano and microsecond photoluminescence kinetics of Ag nanoclusters doped glasses by Quantum Chemistry Methods, and to demonstrate that Ag nanoclusters and Tm3+ ions co-doped oxyfluoride glasses may be applied for white light generation.nrpages: 150status: publishe

Justification of some Aspects of the Choice of Training Means Selection in Track-and-Field Jumps

The chapter deals with the aspects of a take-off in track-and-field jumps with regard to biomechanics and physiological processes. In this chapter, we describe biomechanical and physiological processes underlying the main biomechanisms (BM), which are involved in track-and-field jumps. Our investigation aims at confirmation of the hypothesis that the concept of BM forms the basis of the approach to selecting technique development means in track-and-field. The aim of the first part of the research was to compare the contribution of different BMs. We have analyzed biomechanical parameters of the take-off in a group of elite jumpers (n = 50) during official competitions. Computer simulation modeling was used to detect how an increase in the run-up speed changed the contribution of different BMs. The aim of the second part of the research was to examine the peculiarities of a take-off in special exercises. Findings of the research demonstrated that the take-off in training exercises was performed using relatively independent BMs, similar to those used in competitive jumps. Being dependent on the motor task, key biomechanisms appear to be interdependent on the dynamic level. The role and contribution of the BMs depend on the type of exercise or conditions of its execution, initial conditions, and a motor task set to an athlete

POLYNOMIAL IDENTITIES OF FINITE DIMENSIONAL SIMPLE ALGEBRAS

Let F be an algebraically closed field and let A and B be arbitrary finite dimensional simple algebras over F. We prove that A and B are isomorphic if and only if they satisfy the same identities.CNPq[305344/2009-9]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP[2010/50347-9]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)RFBRRFBR[09-01-00303]RFBR[SSC-1983.2008.1]RFB

An industrial light field camera applied for 3D velocity measurements in flow past confined cylinder

Light field cameras have some advantages over classic cameras in a narrow field of application, such photography, cinematography surveillance and quality control in industry. Light field cameras have larger depth of field, compare to regular camera, but lower spatial resolution along optical axis then binocular system. However, 3D velocity measurements using light field are reasonable alternative to modern 3D PIV measurements. The nature of light field image requires extra reconstruction step which affects overall accuracy. In this article, light field PTV was compared to Tomo-PIV. Both techniques were used to measure 3D velocity fields in a turbulent wake past confined cylinder

Finite-dimensional non-associative algebras and codimension growth

Let A be a (non-necessarily associative) finite-dimensional algebra over a field of characteristic zero. A quantitative estimate of the polynomial identities satisfied by A is achieved through the study of the asymptotics of the sequence of codimensions of A. It is well known that for such an algebra this sequence is exponentially bounded. Here we capture the exponential rate of growth of the sequence of codimensions for several classes of algebras including simple algebras with a special non-degenerate form, finite-dimensional Jordan or alternative algebras and many more. In all cases such rate of growth is integer and is explicitly related to the dimension of a subalgebra of A. One of the main tools of independent interest is the construction in the free non-associative algebra of multialternating polynomials satisfying special properties. (C) 2010 Elsevier Inc. All rights reserved.MIUR of ItalyMIUR of ItalyCNPq[304633/2003-8]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP[2005/60337-2]RFBRRFBR[09-01-00303]RFBR[SSC-1983.2008.1]RFB

An industrial light field camera applied for 3D velocity measurements in flow past confined cylinder

Light field cameras have some advantages over classic cameras in a narrow field of application, such photography, cinematography surveillance and quality control in industry. Light field cameras have larger depth of field, compare to regular camera, but lower spatial resolution along optical axis then binocular system. However, 3D velocity measurements using light field are reasonable alternative to modern 3D PIV measurements. The nature of light field image requires extra reconstruction step which affects overall accuracy. In this article, light field PTV was compared to Tomo-PIV. Both techniques were used to measure 3D velocity fields in a turbulent wake past confined cylinder

Comparative Analysis of the Use of Moderate-Altitude Training by Top Russian and Chinese Athletes

Introduction. The aim of our work was to study the effect of natural hypoxia applied by elite athletes in the course of common training. Data analysed in this paper were collected during joint Russian-Chinese research on the training of elite athletes, who were members of the Russian national team (8 male biathletes, B-team) and 2016 Chinese Olympic team (12 female rowers, R-team)