648 research outputs found
THE INTERACTIONS BETWEEN TWO-SEGMENT STRIKING MOTION GENERATED BY PROXIMAL SEGMENT OF UPPER ARM
The purpose of this study was to examine the kinetical interactions between two segments of the upper arm using the forward dynamics derived from Lagrangeâs equation of motion, and then clarify the proximal-distal sequence. For the decades, open-linked, multi-segment systems were the important issues to biomechanists. But the more segments have been examined, the more complex the topic has become. Therefore, it is important to examine the effects of joint moment on upper extremities striking motion by simulation of two segments. To facilitate dynamic computation and to simplify the modeling, the upper arm of present study was modeled as a two linked-segment model with upper arm and forearm, in which the forearm and hand were treated as one segment. The summation of results is as follows: When the proximal segment was only given a constant moment (free the distal segment), the whole system displayed a proximal-distal sequence. Furthermore, the distal segment lead to the proximal segment, reaching maximum velocity. The motion presented a periodic fluctuation, and would maintain a straight position indefinitely if the duration of motion were sustained long enough
IMMEDIATE EFFECTS OF WARM UP BY OVERWEIGHED BAT IMPLEMENT ON BAT SWING VELOCITY
The purpose of this study was to investigate the immediate effects of warming up by overweighed bat implement on bat swing velocity. Five softball players worked in this experiment and processed the following steps: swing official bat with and without overweight warm-ups (5 and 10 times). The maximal velocity of official bat swing was recorded by a 3-D cinematograph. By one-way ANOVA, the results were described as follows: the maximal velocity of official bat swing after 5-swingings of the overweight bat was greater than that without warm up (F=9.28,
A THREE-DIMENSIONAL ANALYSIS OF THE VOLLEYBALL ONE-FOOT JUMP SPIKE
INTRODUCTION: Since the Chinese National female volleyball team developed the one-foot jump spike technique during the 1980s, the high percentage of successful spiking has made the skill a powerful offensive weapon on volleyball courts all over the world. But no research has been done on the biomechanical analysis of the female one-foot jump spike. The purpose of this study was to describe the biomechanical characteristics of the techniques of the one-foot jump spike demonstrated by elite Taiwanese female players.
METHODS: Four elite female players from the Taiwanese National Volleyball Team served as subjects. Their mean height, weight, and age (and variance) were 1.78 (0.03) m, 63.53 (.11) kg, and 21.50 (.58) years, respectively. Two Peak Performance high speed video cameras operating at 120Hz were synchronized to record the actions employed by the subjects in performing the one-foot jump spike. Three-dimensional object space co-ordinates of digitized image co-ordinates were obtained using a DLT algorithm and 19 calibration points in the video volume.
RESULTS:
[Table 1]
The values of selected variables for the one-foot jump spike by the four female players were calculated (Table 1). The elite female one-foot jump spikers had a shorter takeoff time(0.198s) than the elite male two-foot spikers(0.308s).The female one-foot jump spikers also had a sharper approach angle(27 deg)then the elite male and female two-foot spikers(45- 60 deg) which made it harder for the opponent to block the ball. The results of this study provide valuable information for teachers and coaches teaching players to perform the one-foot jump spike.
CONCLUSIONS: The results indicated that elite female one-foot jump spikers have a shorter takeoff time and a sharper approach angle then the elite male and female two-foot spikers, which contribute to the success of spiking
THE APPLICATION OF RANGE OF MOTION (ROM) AND COORDINATION ON VOLLEYBALL SPIKE
The purpose of this study was to investigate the suitable timing and coordination of body segments during volleyball spike, and find the critical concepts applied on spikinglearning in the air. Cinematography (250 frame/sec, sagittle plane) was used in this study, and Kwon 3D software was used to analyze the timing and coordination of arm swing motion in the air among top and second level female volleyball athletes. The results of this study as following: 1. Enough range of motion (ROM) before ball hitting is the main factor of spiking technique; 2. Proper time-distribution of back-swing, turn-swing and forward-swing cause the proper time of ball hitting. The conclusion of spiking technique was described as following hint concepts: 1. âleadâ: leading back swing at the beginning of takeoff, 2. âpullâ: back swing by pull of elbow and wrist, simultaneously. 3. âturnâ: make a enough ROM of swing phase. 4. âupâ: during up, 5. âhitâ:hitting ball by arm and body momentum
THE COMPARSION OF CURVATURE RADIUS IN DIFFERENT PERFORMANCES
The purpose of this study was to compare the curvature radius of different performance (63.20m and 68.46m) of hammer throw. The subject, who is the present record holder in Taiwan, has 9 years of experience in hammer throw. Two Peak-Performance high-speed video cameras operating at 120Hz were used simultaneously to record the performances of the subject. The results indicated that the patterns were completely different between two performances of hammer throw. The better performance was more periodic than the other. Based on the results of this study, it has been suggested that other sport events that include aspects of rotation may also benefit by adjustment of the pattern from their curvature radius
KINEMATIC ANALYSIS OF TENNIS VOLLEY
The purpose of this study was to examine selected kinematic variables of the tennis volley. Fifteen skilled tennis players performed volley strokes under five (right, rightmiddle, middle, left-middle, left) different lateral contact locations. A ball machine was modified so subjects could not predict the ball trajectory before it was released from the machine. Two high-speed cameras (250Hz) were genlocked to collect the data and the Kwon3D software was used to analyze the temporal and kinematic variables. The results indicated the middle location have the shortest pushing (0.249s) and stroke (0.466s) time than other locations. An ipsilateral side step occurred more often in Backhand (BH, 86%) than in Forehand (FH, 67%). In addition, more FH volley (55%) was used than BH (45%) when return the ball from middle location
A Proton Magnetic Resonance Spectroscopy Study of the Chronic Lead Effect on the Basal Ganglion and Frontal and Occipital Lobes in Middle-Age Adults
An Overview of Regional Experiments on Biomass Burning Aerosols and Related Pollutants in Southeast Asia: From BASE-ASIA and the Dongsha Experiment to 7-SEAS
By modulating the Earth-atmosphere energy, hydrological and biogeochemical cycles, and affecting regional-to-global weather and climate, biomass burning is recognized as one of the major factors affecting the global carbon cycle. However, few comprehensive and wide-ranging experiments have been conducted to characterize biomass-burning pollutants in Southeast Asia (SEA) or assess their regional impact on meteorology, the hydrological cycle, the radiative budget, or climate change. Recently, BASEASIA (Biomass-burning Aerosols in South-East Asia: Smoke Impact Assessment) and the 7-SEAS (7- South-East Asian Studies) Dongsha Experiment were conducted during the spring seasons of 2006 and 2010 in northern SEA, respectively, to characterize the chemical, physical, and radiative properties of biomass-burning emissions near the source regions, and assess their effects. This paper provides an overview of results from these two campaigns and related studies collected in this special issue, entitled Observation, modeling and impact studies of biomass burning and pollution in the SE Asian Environment. This volume includes 28 papers, which provide a synopsis of the experiments, regional weatherclimate, chemical characterization of biomass-burning aerosols and related pollutants in source and sink regions, the spatial distribution of air toxics (atmospheric mercury and dioxins) in source and remote areas, a characterization of aerosol physical, optical, and radiative properties, as well as modeling and impact studies. These studies, taken together, provide the first relatively complete dataset of aerosol chemistry and physical observations conducted in the sourcesink region in the northern SEA, with particular emphasis on the marine boundary layer and lower free troposphere (LFT). The data, analysis and modeling included in these papers advance our present knowledge of source characterization of biomass-burning pollutants near the source regions as well as the physical and chemical processes along transport pathways. In addition, we raise key questions to be addressed by a coming deployment during springtime 2013 in northern SEA, named 7-SEASBASELInE (Biomass-burning Aerosols Stratocumulus Environment: Lifecycles and Interactions Experiment). This campaign will include a synergistic approach for further exploring many key atmospheric processes (e.g., complex aerosol-cloud interactions) and impacts of biomass burning on the surface-atmosphere energy budgets during the lifecycles of biomass burning emissions
Study of deposition parameters for the fabrication of ZnO thin films using femtosecond laser
Femtosecond (fs) pulsed laser deposition (fs-PLD) of ZnO thin film on borosilicate glass substrates is reported in this work. The effect of important fs-PLD parameters such as targetâsubstrate distance, laser pulse energy and substrate temperature on structure, morphology, optical transparency and luminescence of as-deposited films is discussed. XRD analysis reveals that all the films grown using the laser energy range 120â230 ΌJ are polycrystalline when they are deposited at room temperature in a ~10â5 Torr vacuum. Introducing 0.7 mTorr oxygen pressure, the films show preferred c-axis growth and transform into a single-crystal-like film when the substrate temperature is increased to 100 °C. The scanning electron micrographs show the presence of small nano-size grains at 25 °C, which grow in size to the regular hexagonal shape particles at 100 °C. Optical transmission of the ZnO film is found to increase with an increase in crystal quality. Maximum transmittance of 95 % in the wavelength range 400â1400 nm is achieved for films deposited at 100 °C employing a laser pulse energy of 180 ΌJ. The luminescence spectra show a strong UV emission band peaked at 377 nm close to the ZnO band gap. The shallow donor defects increase at higher pulse energies and higher substrate temperatures, which give rise to violet-blue luminescence. The results indicate that nano-crystalline ZnO thin films with high crystalline quality and optical transparency can be fabricated by using pulses from fs lasers
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
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