209 research outputs found
PRESSURE DISTRIBUTION OF THE FIST IN PUSH-UP EXERCISES OF KARATE COMPETITORS
This report presents an empirical study of pressures distributed within the fingers of karate competitors while the subjects performed static and dynamic push-up exercises on their fists on a hard floor. As was expected, results revealed that peak pressures were localized in the index and middle fingers of the karate competitors during both the static and dynamic modes whereas the pressure was uniformly distributed in all fingers, except the thumb, in a control group of untrained college students. To avoid permanent hand injuries and an eventual reduction in gripping strength due to highly concentrated pressures, wearing adequate protective knuckle pads should be enforced in all matches and push-up exercises in karate training
THE EFFECTS OF GOLF SHAFT AND CLUBHEAD ON THE VELOCITY OF CLUB-HEAD AND BALL
The purpose of this study was to investigate 1) the influence of the bending stiffness of the golf shaft on the velocity of the club-head and the ball, and 2) the influence of different club-heads on the velocity of the club-head and the ball. Four different drivers made up of two different shaft stiffness (R-stiff, L-flexible) and club head (Titanium, Graphite) were used in the experiments. The results showed that the shaft stiffness L resulted in slower before-impact club head velocity than the shaft stiffness R, whereas the shaft stiffness L resulted in higher maximum ball velocity than shaft stiffness R. But the result in the statistics showed no significant club-head material effect on either clubhead velocity or the ball velocity. And there was no significant shaft stiffness effect on either club-head velocity or the ball velocity
EFFECT OF EXHAUSTIVE UPHILL RUNNING ON KNEE JOINT MOTION DURING THE STANCE PHASE OF RUNNING
The purpose of this study was to imitate an exhaustive outdoor mountain road uphill running and investigate the effect on knee joint motion angles during the stance phase of running. Knee joint kinematical data collected from 8 male recreational runners running at 10 km/hr on a level treadmill prior to and following exhaustive uphill running revealed differences in flexion angles. These results demonstrated that exhaustive running can have an effect on knee joint running movement pattern. Due to these findings, the human natural movement control may be adjusted and the maintenance of preferred or optimal movement path costs more efforts which possibly play a role in many common lower extremity running injuries. This relevance may be applied to the future designing of assistive performance control shoes
THE RESPONSE OF WHOLE BODY VIBRATION ON TAI CHI AND WEIGHT-LIFTING ATHLETES
Whole body vibration (WBV) is a new technique which may improve leg muscle strength. Many researchers have studied the effect of whole body vibration recently. But study of effects of vibration stimulus to different activity type athletes, such as Tai Chi (N=12) and Weight-lifting (N=15) athletes is lacking. In this study we examine that question. The subjects were asked to stand in a half-squat posture without additional load on a vibration platform with 7 vibration frequencies (5, 9, 12, 16, 20, 24, 30 Hz) at 4 mm amplitude and maintained for 30 seconds. The effect of WBV would be different on different sport subjects’ perceived exertion. We discovered that the subject’s perception may be related with the acceleration of the subject’s head. Using whole body vibration training to improve muscle power and strength depends on the particular sport’s training emphasis to setup the appropriate training protocol such as amplitude and frequency
Author Correction: Changes in Distribution of Dry Eye Disease by the New 2016 Diagnostic Criteria from the Asia Dry Eye Society.
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper
Multi-user video streaming using unequal error protection network coding in wireless networks
In this paper, we investigate a multi-user video streaming system applying unequal error protection (UEP) network coding (NC) for simultaneous real-time exchange of scalable video streams among multiple users. We focus on a simple wireless scenario where users exchange encoded data packets over a common central network node (e.g., a base station or an access point) that aims to capture the fundamental system behaviour. Our goal is to present analytical tools that provide both the decoding probability analysis and the expected delay guarantees for different importance layers of scalable video streams. Using the proposed tools, we offer a simple framework for design and analysis of UEP NC based multi-user video streaming systems and provide examples of system design for video conferencing scenario in broadband wireless cellular networks
Observation of the nonlinear Hall effect under time reversal symmetric conditions
The electrical Hall effect is the production of a transverse voltage under an
out-of-plane magnetic field. Historically, studies of the Hall effect have led
to major breakthroughs including the discoveries of Berry curvature and the
topological Chern invariants. In magnets, the internal magnetization allows
Hall conductivity in the absence of external magnetic field. This anomalous
Hall effect (AHE) has become an important tool to study quantum magnets. In
nonmagnetic materials without external magnetic fields, the electrical Hall
effect is rarely explored because of the constraint by time-reversal symmetry.
However, strictly speaking, only the Hall effect in the linear response regime,
i.e., the Hall voltage linearly proportional to the external electric field,
identically vanishes due to time-reversal symmetry. The Hall effect in the
nonlinear response regime, on the other hand, may not be subject to such
symmetry constraints. Here, we report the observation of the nonlinear Hall
effect (NLHE) in the electrical transport of the nonmagnetic 2D quantum
material, bilayer WTe2. Specifically, flowing an electrical current in bilayer
WTe2 leads to a nonlinear Hall voltage in the absence of magnetic field. The
NLHE exhibits unusual properties sharply distinct from the AHE in metals: The
NLHE shows a quadratic I-V characteristic; It strongly dominates the nonlinear
longitudinal response, leading to a Hall angle of about 90 degree. We further
show that the NLHE directly measures the "dipole moment" of the Berry
curvature, which arises from layer-polarized Dirac fermions in bilayer WTe2.
Our results demonstrate a new Hall effect and provide a powerful methodology to
detect Berry curvature in a wide range of nonmagnetic quantum materials in an
energy-resolved way
Autosomal dominant craniometaphyseal dysplasia is caused by mutations in the transmembrane protein ANK
Craniometaphyseal dysplasia (CMD) is a rare skeletal disorder characterized by progressive thickening and increased mineral density of craniofacial bones and abnormally developed metaphyses in long bones. Linkage studies mapped the locus for the autosomal dominant form of CMD to an similar to5-cM interval on chromosome 5p, which is defined by recombinations between loci D5S810 and D5S1954. Mutational analysis of positional candidate genes was performed, and we describe herein three different mutations, in five different families and in isolated cases, in ANK, a multipass transmembrane protein involved in the transport of intracellular pyrophosphate into extracellular matrix. the mutations are two in-frame deletions and one in-frame insertion caused by a splicing defect. All mutations cluster within seven amino acids in one of the six possible cytosolic domains of ANK. These results suggest that the mutated protein has a dominant negative effect on the function of ANK, since reduced levels of pyrophosphate in bone matrix are known to increase mineralization.Harvard Sch Dent Med, Forsyth Inst, Harvard Forsyth Dept Oral Biol, Boston, MA 02115 USAHarvard Univ, Sch Med, Childrens Hosp, Dept Cell Biol, Boston, MA USAHarvard Univ, Sch Med, Childrens Hosp, Dept Genet, Boston, MA USAHarvard Univ, Sch Med, Childrens Hosp, Div Plast Surg, Boston, MA USAUniversidade Federal de São Paulo, EPM, Campinas, SP, BrazilInst Cirurg Plast Craniofacial SOBRAPAR, Campinas, SP, BrazilShowa Univ, Sch Med, Dept Plast & Reconstruct Surg, Tokyo 142, JapanVirginia Commonwealth Univ, Med Coll Virginia, Dept Human Genet, Richmond, VA 23298 USASt Louis Univ, Sch Med, Cardinal Glennon Childrens Hosp, Div Med Genet, St Louis, MO 63104 USAUniv Cape Town, Sch Med, Dept Human Genet, ZA-7925 Cape Town, South AfricaOhio State Univ, Coll Dent, Dept Orthodont, Columbus, OH 43210 USAChildrens Hosp, Dept Genet, Columbus, OH 43205 USAUniv Minnesota, Sch Dent, Dept Oral Biol & Genet, Minneapolis, MN 55455 USAUniversidade Federal de São Paulo, EPM, Campinas, SP, BrazilWeb of Scienc
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