scholarly journals Phase analysis in maximal sprinting: an investigation of step-to-step technical changes between the initial acceleration, transition and maximal velocity phases

2018 ◽  
Vol 19 (2) ◽  
pp. 141-156 ◽  
Author(s):  
Hans C. von Lieres und Wilkau ◽  
Gareth Irwin ◽  
Neil E. Bezodis ◽  
Scott Simpson ◽  
Ian N. Bezodis
Keyword(s):  
Phase Analysis ◽  
Maximal Velocity ◽  
Initial Acceleration

scholarly journals Phase analysis in maximal sprinting: an investigation of step-to-step technical changes between the initial acceleration, transition and maximal velocity phases.

2017 ◽  
Author(s):  
Hans Cristian von Lieres und Wilkau ◽  
Gareth Irwin ◽  
Neil E. Bezodis ◽  
Scott Simpson ◽  
Ian N. Bezodis
Keyword(s):  
Phase Analysis ◽  
Sagittal Plane ◽  
Maximum Velocity ◽  
Transition Phase ◽  
Maximal Velocity ◽  
Centre Of Mass ◽  
Acceleration Phase ◽  
Video Cameras ◽  
Large Step ◽  
Initial Acceleration

The aim of this study was to investigate spatiotemporal and kinematic changes between the initial acceleration, transition and maximum velocity phases of a sprint. Sagittal plane kinematics from five experienced sprinters performing 50 m maximal sprints were collected using six HD-video cameras. Following manual digitising, spatiotemporal and kinematic variables at touchdown and toe-off were calculated. The start and end of the transition phase were identified using the step to step changes in centre of mass height and segment angles. Mean step to step changes of spatiotemporal and kinematic variables during each phase were calculated. Firstly, the study showed that if sufficient trials are available, step-to-step changes in shank and trunk angles might provide an appropriate measure to detect sprint phases in applied settings. However, given that changes in centre of mass height represent a more holistic measure, this was used to sub-divide the sprints into separate phases. Secondly, during the initial acceleration phase large step to step changes in touchdown kinematics were observed compared to the transition phase. At toe-off, step-to-step kinematic changes were consistent across the initial acceleration and transition phases before plateauing during the maximal velocity phase. These results provide coaches and practitioners with valuable insights into key differences between phases in maximal sprinting.

scholarly journals The importance of duration and magnitude of force application to sprint performance during the initial acceleration, transition and maximal velocity phases

2020 ◽  
Vol 38 (20) ◽  
pp. 2359-2366
Author(s):  
Hans C. von Lieres Und Wilkau ◽  
Neil E. Bezodis ◽  
Jean-Benoît Morin ◽  
Gareth Irwin ◽  
Scott Simpson ◽  
...  
Keyword(s):  
Sprint Performance ◽  
Maximal Velocity ◽  
Force Application ◽  
Initial Acceleration

X-ray phase analysis in leucite systems

2007 ◽  
Vol 2007 (suppl_26) ◽  
pp. 531-536 ◽  
Author(s):  
J. Maixner ◽  
A. Kloužková ◽  
M. Mrázová ◽  
M. Kohoutková
Keyword(s):  
Phase Analysis ◽  
X Ray

THE INFLUENCE OF ETHANOL ON THE CONVERSION OF PREGNENOLONE TO PROGESTERONE BY HUMAN PLACENTAL MICROSOMES

1974 ◽  
Vol 76 (1) ◽  
pp. 178-188 ◽  
Author(s):  
H. Lübbert ◽  
K. Pollow ◽  
R. Wagner ◽  
J. Hammerstein
Keyword(s):  
Kinetic Parameters ◽  
Enzyme Preparation ◽  
Ethanol Concentration ◽  
Hydroxysteroid Dehydrogenase ◽  
Product Formation ◽  
Linear Increase ◽  
Maximal Velocity ◽  
Microsomal Enzyme ◽  
Temperature Optima ◽  
Substrate Concentrations

ABSTRACT The effects of ethanol on kinetic parameters of placental Δ5-3β-hydroxysteroid dehydrogenase were studied. In the presence of high pregnenolone concentrations (50 μm, [S] > Km) the microsomal enzyme preparation exhibited an almost linear increase in activity as the ethanol concentration in the medium was raised from 2.5 to 15 % (v/v). At lower substrate concentrations ([S] << Km) ethanol caused inhibition. Other effects of ethanol were: linearity of product formation with time was prolonged; the maximal velocity was markedly increased; the Km for pregnenolone slightly decreased with increasing ethanol concentrations (2.5 to 10 %, v/v) whereas the Km for NAD remained the same. The pH and temperature optima of the reaction were unaffected by ethanol. Other organic solvents caused similar effects.

Local Lattice Strain Measurement Using Geometric Phase Analysis of Dark Field Images from Scanning Transmission Electron Microscopy

2011 ◽  
Author(s):  
Jayhoon Chung ◽  
Guoda Lian ◽  
Lew Rabenberg
Keyword(s):  
Phase Analysis ◽  
Geometric Phase ◽  
Process Development ◽  
Local Strain ◽  
Strain Engineering ◽  
Dark Field ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Geometric Phase Analysis ◽  
Scanning Transmission

Abstract Since strain engineering plays a key role in semiconductor technology development, a reliable and reproducible technique to measure local strain in devices is necessary for process development and failure analysis. In this paper, geometric phase analysis of high angle annular dark field - scanning transmission electron microscope images is presented as an effective technique to measure local strains in the current node of Si based transistors.

Chemisorption of ethylene on nickel surfaces with preadsorbed oxygen

1981 ◽  
Vol 46 (2) ◽  
pp. 340-353
Author(s):  
Pavel Zachař ◽  
Zdeněk Bastl ◽  
Jakub Adámek
Keyword(s):  
Gas Phase ◽  
Phase Analysis ◽  
Oxygen Concentration ◽  
Electrical Resistance ◽  
High Vacuum ◽  
Volumetric Method ◽  
Surface Oxygen ◽  
Oxygen Chemisorption ◽  
Thin Polycrystalline ◽  
Total Adsorption

Chemisorption of ethylene was studied on thin polycrystalline layers of nickel prepared by metal deposition in high vacuum and modified by preadsorbed oxygen. The volumetric method combined with the gas-phase analysis and the measurement of the electrical resistance changes of these layers were used. Already small amounts of preadsorbed oxygen of the order of 10-2 of the monolayer affect rather substantially the extent of ethylene chemisorption. The extent of the initial irreversible chemisorption and also the total adsorption of ethylene as a function of the amount of preadsorbed oxygen have a maximum at the surface oxygen concentration of 3 . 1013 molecule cm-2. The adsorption accompanied by the extensive dissociation of ethylene C-H bonds proceeds predominantly on nickel atoms with lower coordination (atoms on the microcrystal edges, corner atoms, etc.), where also oxygen chemisorption proceeds preferentially.

Peroxidases from Tulip Bulbs (Tulipa fosteriana, L.) Oxidize Xenobiotics NNitrosodimethylamine and N-Nitroso-N-methylaniline in vitro

1997 ◽  
Vol 62 (11) ◽  
pp. 1804-1814 ◽  
Author(s):  
Marie Stiborová ◽  
Hana Hansíková
Keyword(s):  
Cytochromes P450 ◽  
Kinetic Studies ◽  
The Other ◽  
Maximal Velocity ◽  
Michaelis Constant ◽  
Other Hand ◽  
Plant Peroxidases ◽  
Tulip Bulbs

Tulip bulbs (Tulipa fosteriana, L.) contain peroxidases catalyzing the oxidation of the xenobiotics N-nitrosodimethylamine (NDMA) and N-nitroso-N-methylaniline (NMA). Three anionic (A1, A2, A3) and four cationic (B, C, D, E) peroxidases were purified from this tissue, partially characterized and used for kinetic studies. Demethylation of NDMA and NMA producing formaldehyde is catalyzed by one anionic (A1) and three cationic (C, D, E) peroxidases. The oxidation of NDMA by tulip peroxidases exhibits the Michaelis-Menten kinetics. The apparent Michaelis constant and the maximal velocity values for this substrate were determined. On the other hand, non-Michaelian kinetics for the NMA oxidation were observed with tulip peroxidases. The most abundant cationic peroxidase (peroxidase C) was used for detailed enzymatic studies. In addition to formation of formaldehyde, methylaniline, aniline, 4-aminophenol and phenol were found to be metabolites formed from NMA. Phenol was formed presumably by N-demethylation via a benzenediazonium ion, while methylaniline, aniline and 4-aminophenol were products of denitrosation of the substrate. The efficiencies of plant peroxidases to oxidize NDMA and NMA in vitro are compared with those of cytochromes P450 and discussed.

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