排序方式： 共有7条查询结果，搜索用时 15 毫秒
1
1.
Accelerometer-based systems are often used to quantify human movement. This study’s aim was to assess the reliability and validity of the Myotest® accelerometer-based system for measuring running stride kinematics. Twenty habitual runners ran two 60 m trials at 12, 15, 18 and 21 km·h?1. Contact time, aerial time and step frequency parameters from six consecutive running steps of each trial were extracted using Myotest® data. Between-trial reproducibility of measures was determined by comparing kinematic parameters from the two runs performed at the same speed. Myotest® measures were compared against photocell-based (Optojump Next®) and high-frequency video data to establish concurrent validity. The Myotest®-derived parameters were highly reproducible between trials at all running speeds (intra-class correlation coefficient (ICC): 0.886 to 0.974). Compared to the photo-cell and high-speed video-based measures, the mean contact times from the Myotest® were 34% shorter and aerial times were 64% longer. Only step frequency was comparable between systems and demonstrated high between-system correlation (ICC ≥ 0.857). The Myotest® is a practical portable device that is reliable for measuring contact time, aerial time and step frequency during running. In terms of validity, it provides accurate step frequency measures but underestimates contact time and overestimates aerial time compared to photocell- and optical-based systems. 相似文献
2.
Rupprecht P Golé L Rieu JP Vézy C Ferrigno R Mertani HC Rivière C 《Biomicrofluidics》2012,6(1):14107-1410712
We have developed a method for studying cellular adhesion by using a custom-designed microfluidic device with parallel non-connected tapered channels. The design enables investigation of cellular responses to a large range of shear stress (ratio of 25) with a single input flow-rate. For each shear stress, a large number of cells are analyzed (500–1500 cells), providing statistically relevant data within a single experiment. Besides adhesion strength measurements, the microsystem presented in this paper enables in-depth analysis of cell detachment kinetics by real-time videomicroscopy. It offers the possibility to analyze adhesion-associated processes, such as migration or cell shape change, within the same experiment. To show the versatility of our device, we examined quantitatively cell adhesion by analyzing kinetics, adhesive strength and migration behaviour or cell shape modifications of the unicellular model cell organism Dictyostelium discoideum at 21 °C and of the human breast cancer cell line MDA-MB-231 at 37 °C. For both cell types, we found that the threshold stresses, which are necessary to detach the cells, follow lognormal distributions, and that the detachment process follows first order kinetics. In addition, for particular conditions’ cells are found to exhibit similar adhesion threshold stresses, but very different detachment kinetics, revealing the importance of dynamics analysis to fully describe cell adhesion. With its rapid implementation and potential for parallel sample processing, such microsystem offers a highly controllable platform for exploring cell adhesion characteristics in a large set of environmental conditions and cell types, and could have wide applications across cell biology, tissue engineering, and cell screening. 相似文献
3.
Celine Triolet Nicolas Benguigui Cyrille Le Runigo A. Mark Williams 《Journal of sports sciences》2013,31(8):820-830
Abstract We quantify the nature and frequency of anticipation behaviours in professional tennis using video coding of incidents where the time delay between the opponent's stroke and the reaction of the player were recorded. We argue that anticipation is based on uncertain information and should lead in some situations to erroneous decisions. We identified the transition between reaction (with 100% accuracy in the selection of where the ball is played on the court) and anticipation (with less than 100% accuracy) as being 140–160 ms after ball contact. Anticipation behaviours occurred on between 6.14% and 13.42% of the coded situations. These anticipation behaviours appeared almost exclusively in ‘unfavourable’ situations, where the opponent had a significant tactical advantage, with the type of playing surface having only a limited effect. Moreover, the decrease in accuracy with shorter response times is not monotonic, with an increase in response accuracy being observed for times shorter than 120 ms before ball contact. We propose that very early anticipation behaviours occur when players use significant context-specific information before the opponent's stroke. When such information is not available, players produce anticipation behaviours that are closer to the moment of ball–racket contact using information that is more likely to be based on the opponent's preparation of the stroke. This study opens new directions for research focusing on the testing and training of anticipation in fast ball sports. 相似文献
4.
Li Wang Yu Li Xiao-Yu Yang Bo-Bo Zhang Nelle Ninane Henk J Busscher Zhi-Yi Hu Cyrille Delneuville Nan Jiang Hao Xie Gustaaf Van Tendeloo Tawfique Hasan Bao-Lian Su 《国家科学评论(英文版)》2021,8(4)
Like nanomaterials, bacteria have been unknowingly used for centuries. They hold significant economic potential for fuel and medicinal compound production. Their full exploitation, however, is impeded by low biological activity and stability in industrial reactors. Though cellular encapsulation addresses these limitations, cell survival is usually compromised due to shell-to-cell contacts and low permeability. Here, we report ordered packing of silica nanocolloids with organized, uniform and tunable nanoporosities for single cyanobacterium nanoencapsulation using protamine as an electrostatic template. A space between the capsule shell and the cell is created by controlled internalization of protamine, resulting in a highly ordered porous shell-void-cell structure formation. These unique yolk-shell nanostructures provide long-term cell viability with superior photosynthetic activities and resistance in harsh environments. In addition, engineering the colloidal packing allows tunable shell-pore diameter for size-dependent permeability and introduction of new functionalities for specific molecular recognition. Our strategy could significantly enhance the activity and stability of cyanobacteria for various nanobiotechnological applications. 相似文献
5.
Cyrille A. C. Van Bragt Anouke W. E. A. Bakx Theo C. M. Bergen Marcel A. Croon 《Higher Education》2011,61(1):59-75
The central goal of this study is to clarify to what degree former education and students’ personal characteristics (the ‘Big
Five personality characteristics’, personal orientations on learning and students’ study approach) may predict study outcome
(required credits and study continuance). Analysis of the data gathered through questionnaires of 1,471 Universities of Applied
Sciences students make clear that former Education did not come forth as a powerful predictor for Credits or Study Continuance.
Significant predictors are Conscientiousness and Ambivalence and Lack of Regulation. The higher the scores on Conscientiousness
the more credits students are bound to obtain and the more likely they will continue their education. On the other hand students
with high scores on Ambivalence and Lack of Regulation will most likely obtain fewer Credits or drop out more easily. The
question arises what these results mean for the present knowledge economy which demands an increase of inhabitants with an
advanced level of education. Finally, implications and recommendations for future research are suggested. 相似文献
6.
7.
Thibault Lussiana Cyrille Gindre Laurent Mourot Kim Hébert-Losier 《European Journal of Sport Science》2017,17(7):847-857
Running patterns are often categorized into subgroups according to common features before data analysis and interpretation. The Volodalen® method is a simple field-based tool used to classify runners into aerial or terrestrial using a 5-item subjective rating scale. We aimed to validate the Volodalen® method by quantifying the relationship between its subjective scores and 3D biomechanical measures. Fifty-four runners ran 30?s on a treadmill at 10, 12, 14, 16, and 18?km?h?1 while their kinematics were assessed subjectively using the Volodalen® method and objectively using 3D motion capture. For each runner and speed, two researchers scored the five Volodalen® items on a 1-to-5 scale, which addressed vertical oscillation, upper-body motion, pelvis and foot position at ground contact, and footstrike pattern. Seven 3D biomechanical parameters reflecting the subjective items were also collected and correlated to the subjective scores. Twenty-eight runners were classified as aerial and 26 as terrestrial. Runner classification did not change with speed, but the relative contribution of the biomechanical parameters to the subjective classification was speed dependent. The magnitude of correlations between subjective and objective measures ranged from trivial to very large. Five of the seven objective parameters significantly differed between aerial and terrestrial runners, and these parameters demonstrated the strongest correlations to the subjective scores. Our results support the validity of the Volodalen® method, whereby the visual appreciation of running gait reflected quantifiable objective parameters. Two minor modifications to the method are proposed to simplify its use and improve agreement between subjective and objective measures. 相似文献
1