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1
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Intra-Personal and Inter-Personal Kinetic Synergies During Jumping

100%
Slomka K., Juras G., Sobota G., Furmanek M., Rzepko M., Latash M. L.
Journal of Human Kinetics
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2015
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vol. 49
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issue 1
75-88
EN
We explored synergies between two legs and two subjects during preparation for a long jump into a target. Synergies were expected during one-person jumping. No such synergies were expected between two persons jumping in parallel without additional contact, while synergies were expected to emerge with haptic contact and become stronger with strong mechanical contact. Subjects performed jumps either alone (each foot standing on a separate force platform) or in dyads (parallel to each other, each person standing on a separate force platform) without any contact, with haptic contact, and with strong coupling. Strong negative correlations between pairs of force variables (strong synergies) were seen in the vertical force in one-person jumps and weaker synergies in two-person jumps with the strong contact. For other force variables, only weak synergies were present in one-person jumps and no negative correlations between pairs of force variable for two-person jumps. Pairs of moment variables from the two force platforms at steady state showed positive correlations, which were strong in one-person jumps and weaker, but still significant, in two-person jumps with the haptic and strong contact. Anticipatory synergy adjustments prior to action initiation were observed in oneperson trials only. We interpret the different results for the force and moment variables at steady state as reflections of postural sway.
2
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Motor Control: In Search of Physics of the Living Systems

100%
Latash M.
Journal of Human Kinetics
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2010
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vol. 24
7-18
EN
This review contrasts two approaches to motor control that have dominated the field over the past years. One of them is built on ideas of the control theory; it assumes that neuronal structures perform computations and operates with notions such as motor programs and internal models. The alternative approach is based on physics and neurophysiology. It refutes the assumption of neural computations and operates with such notions as neuronal thresholds and equilibrium states. The two approaches have different goals. The former tries to produce a formal description of how any system, irrespective of its physics and physiology, can produce typical features of biological movement. This research may be very productive and important for such fields as robotics and prosthetics. The latter approach tries to produce a formal description of how neuromotor processes within the actual systems for movement production (for example, the human body) are organized to produce coordinated movements. Its goal is to turn motor control into a subfield of physics of living systems. Recent developments of the equilibrium-point hypothesis, referent configuration hypothesis, and the ideas of synergic control represent important steps towards achieving this goal.
3
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The Relationships Between the Effectiveness of Team Play and the Sporting Level of A Team

88%
Panfil R., Superlak E.
Human Movement
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2012
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vol. 13
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issue 2
152-160
EN
Purpose. This study aimed at determining what relationships exist between the determinants of team play efficiency (cooperation) for creating scoring situations in volleyball and the sporting level of a team. These relationships take into consideration the number of players who cooperate within a team and the speed at which sets are performed. Methods. The study gathered observational data on how three leading male volleyball teams, namely Brazil, Russia and Serbia, played in the semi-finals of the 2010 World League, finishing first, second and fourth, respectively. The research tool was a self-made data registration sheet which included the description of the chosen variables, namely the type of plays used and how sets were formed, and the criteria for their quantification. The collected results were presented as tables and indexes. An interdisciplinary interpretation of the results was conducted, which included a qualitative identification of the dependencies that existed between the chosen variables. Results. The efficiency of team cooperation when solving situational problems in the offense was not significantly different in the analysed teams. The prevailing activities during the game were those performed in the 2nd tempo, i.e. team play requiring the coordination and synchronization of three players. Players' activity as well as the performance efficiency of the sets they performed in the 2nd tempo increased along with an increase in the sporting efficiency of the examined teams. In the case of sets performed in the 3rd tempo, activity and the efficiency of coordination declined along with the growth of sports efficiency. The suggested indexes of the employment and application of synergy enable us to determine its level within the teams which differ in regards to sports efficiency. A diagnostic value of the index of synergy usage, which is determined by the efficiency of sets in various paces, is higher than a diagnostic value of the index that is determined by the activity of team play. Conclusions. Nowadays, sport teams, especially those which play volleyball at the highest world level, are characterized by a high level of dynamic organization of players' activities, which is manifested in the game with the high efficiency of team play when solving situational problems in the offense, particularly with the use of two or three players conducted in the 1st and 2nd tempos.
4
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Movements that are both variable and optimal

88%
Latash M. L.
Journal of Human Kinetics
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2012
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vol. 34
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issue 1
5-13
EN
This brief review addresses two major aspects of the neural control of multi-element systems. First, the principle of abundance suggests that the central nervous system unites elements into synergies (co-variation of elemental variables across trials quantified within the framework of the uncontrolled manifold hypothesis) that stabilize important performance variables. Second, a novel method, analytical inverse optimization, has been introduced to compute cost functions that define averaged across trials involvement of individual elements over a range of values of task-specific performance variables. The two aspects reflect two features of motor coordination: (1) using variable solutions that allow performing secondary tasks and stabilizing performance variables; and (2) selecting combinations of elemental variables that follow an optimization principle. We suggest that the conflict between the two approaches (a single solution vs. families of solutions) is apparent, not real. Natural motor variability may be due to using the same cost function across slightly different initial states; on the other hand, there may be variability in the cost function itself leading to variable solutions that are all optimal with respect to slightly different cost functions. The analysis of motor synergies has revealed specific changes associated with atypical development, healthy aging, neurological disorders, and practice. These have allowed formulating hypotheses on the neurophysiological mechanisms involved in the synergic control of actions.
5
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Hydrodechlorination of tetrachloromethane over silica-supported palladium-gold alloys

88%
Karpiński Z., Bonarowska M., Juszczyk W.
Polish Journal of Chemical Technology
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2014
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vol. 16
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issue 4
101-105
EN
Compared with the monometallic palladium, bimetallic Pd-Au/SiO2 catalysts show much higher activity and better stability in the reaction of hydrodechlorination of tetrachloromethane, also providing higher selectivity to longer than methane hydrocarbon products. Reasonably mixed Pd-Au particles show better catalytic performance during ~60 h operation, whereas the monometallic palladium and very rich in palladium catalysts suffer rapid deactivation. Smaller amounts of carbon- and chlorine-containing deposits found after reaction on Pd-Au catalysts correspond to their superior catalytic behavior.
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