The Influence of Court Surfaces on Lower Limb Muscle Activation of Tennis Run-and-Stroke

This study aimed to examine the characteristics of lower extremity muscle activity between different tennis court surfaces. Six male right-handed elite tennis players were recruited, and their electromyography activity (EMG) during open stance running forehand were collected. Average activity level of rectus femoris (RF), biceps femoris (BF), gastrocnemius (GAS), tibialis anterior (TA) from the lead leg, which normalized by maximal voluntary isometric contractions (MVC) was recorded under different situation (hard court, grass court, clay court). Our study demonstrates that GAS was significantly different and the activation level was greater on a hard court than on clay (p = .005). Tennis players should enhance their gastrocnemius muscle performance when matching from clay to hard court to avoid a higher level of gastrocnemius activation when adapting to a different court, which could lead to an injury. KEYWORDS: Grand Slam, training, EMG, performanc

Factors Related to Intra-Tendinous Morphology of Achilles Tendon in Runners

The purpose of this study was to determine and explore factors (age, sex, anthropometry, running and injury/pain history, tendon gross morphology, neovascularization, ankle range of motion, and ankle plantarflexor muscle endurance) related to intra-tendinous morphological alterations of the Achilles tendon in runners. An intra-tendinous morphological change was defined as collagen fiber disorganization detected by a low peak spatial frequency radius (PSFR) obtained from spatial frequency analysis (SFA) techniques in sonography. Ninety-one runners (53 males and 38 females; 37.9 ± 11.6 years) with 8.8 ± 7.3 years of running experience participated. Height, weight, and waist and hip circumferences were recorded. Participants completed a survey about running and injury/pain history and the Victorian Institute of Sport Assessment-Achilles (VISA-A) survey. Heel raise endurance and knee-to-wall composite dorsiflexion were assessed. Brightness-mode (B-mode) sonographic images were captured longitudinally and transversely on the Achilles tendon bilaterally. Sonographic images were analyzed for gross morphology (i.e., cross-sectional area [CSA]), neovascularization, and intra-tendinous morphology (i.e., PSFR) for each participant. The factors associated with altered intra-tendinous morphology of the Achilles tendon were analyzed using a generalized linear mixed model. Multivariate analyses revealed that male sex was significantly associated with a decreased PSFR. Additionally, male sex and the presence of current Achilles tendon pain were found to be significantly related to decreased PSFR using a univariate analysis. Our findings suggested that male sex and presence of current Achilles tendon pain were related to intra-tendinous morphological alterations in the Achilles tendon of runners

KINEMATICS ANALYSIS OF THE UPPER EXTREMITY DURING THE TWOHANDED BACKHAND DRIVE VOLLEY FOR FEMALE TENNIS PLAYERS

The purpose of this study was to discuss the motion characteristics of the arms in the two-handed backhand drive volley. Five elite female tennis players participated in this study, their two-handed backhand drive volley strokes were analysed, and all participants are right handed. Motion Analysis System with 10 Eagle Digital inferred high speed cameras at 200Hz were used for this study. The results show a similar elbow and wrist speed strategy in x-axis between two-handed ground stroke and drive volley, our study also found that the rear arm dominates the stroke and mainly provide the topspin that is required for the skill of the drive volley. In order to create better stroke efficiency, the right elbow reached peak velocity first, followed by the right wrist before racket impact with the ball

Self‐potential ambient noise and spectral relationship with urbanization, seismicity, and strain rate revealed via the Taiwan Geoelectric Monitoring Network

AbstractGeoelectric self‐potential (SP) signals are sensitive to natural and anthropogenic factors. The SP spectral characteristics under the different factors in Taiwan were investigated, and the SP spectral scalings were correlated with urbanization level, seismicity, and crustal deformation. The ambient SP noise models were first established by estimating the probability density functions of the spectrograms at each frequency. The effects of the natural and anthropogenic factors on the SP signals are understood by comparing the SP noise models under various conditions, such as precipitation, urbanization, and electric trains. Results show that the SP signals in areas of high industrialization and human activity and areas close to train stations behave as white noises and exhibit a distinct spectral ripple at frequencies around 1 Hz. On the other hand, the SP spectral power law parameters, Gutenberg‐Richter b values, and dilation strain rates were estimated by using the SP, earthquake catalog, and GPS data, respectively, during 2012–2017. By investigating the correlations of the SP spectral parameters with the Gutenberg‐Richter b value, dilation strain rates, and urbanization level, the SP optimal frequency band is found between 0.006 and 1 Hz due to the high correlation between the SP and seismicity data and between the SP and dilation data and the low correlation between the SP and urbanization data. Hence, this study may help the filtering and screening of the SP data and facilitate the understanding of the mechano‐electric behavior in the crust

Structured LDPC codes with low error floor based on PEG Tanner graphs

Abstract-Progressive edge-growth (PEG) algorithm was proven to be a simple and effective approach to design good LDPC codes. However, the Tanner graph constructed by PEG algorithm is non-structured which leads the positions of 's of the corresponding parity check matrix fully random. In this paper, we propose a general method based on PEG algorithm to construct structured Tanner graphs. These hardware-oriented LDPC codes can reduce the VLSI implementation complexity. Similar to PEG method, our CP-PEG approach can be used to construct both regular and irregular Tanner graphs with flexible parameters. For the consideration of encoding complexity and error floor, the modifications of proposed algorithm are discussed. Simulation results show that our codes, in terms of bit error rate (BER) or packet error rate (PER), outperform other PEG-based LDPC codes and are better than the codes in IEEE 802.16e

Optically Defined Modal Sensors Incorporating Spiropyran-Doped Liquid Crystals with Piezoelectric Sensors

We integrated a piezoelectric sensing layer lamina containing liquid crystals (LC) and spiropyran (SP) in a LC/SP mixture to create an optically reconfigurable modal sensor for a cantilever beam. The impedance of this LC/SP lamina was decreased by UV irradiation which constituted the underlying mechanism to modulate the voltage externally applied to the piezoelectric actuating layer. Illuminating a specific pattern onto the LC/SP lamina provided us with a way to spatially modulate the piezoelectric vibration signal. We showed that if an UV illuminated pattern matches the strain distribution of a specific mode, a piezoelectric modal sensor can be created. Since UV illumination can be changed in situ in real-time, our results confirm for the first time since the inception of smart sensors, that an optically tailored modal sensor can be created. Some potential applications of this type of sensor include energy harvesting devices, bio-chips, vibration sensing and actuating devices

Protective Effects of Morus Root Extract (MRE) Against Lipopolysaccharide-Activated RAW264.7 Cells and CCl4-Induced Mouse Hepatic Damage

Background/Aims: Inflammation is one of the main contributors to chronic diseases such as cancer. It is of great value to identify the potential activity of various medicinal plants for regulating or blocking uncontrolled chronic inflammation. We investigated whether the root extract of Morus australis possesses antiinflammatory and antioxidative stress potential and hepatic protective activity. Methods: The microwave-assisted extractionwere was used to prepare the ethanol extract from the dried root of Morus australis (MRE), including polyphenolic and flavonoid contents. Lipopolysaccharide (LPS)-stimulated RAW264.7 cells was examined the anti-inflammatory and anti-oxidative potential of MRE. CCl4-induced mouse hepatic damage were performed to detect the hepatic protective potential in vivo. Immunohistochemistry (IHC) and western blot assays were used to detect target proteins. Results: MRE contained approximately 23% phenolic compounds and 3% flavonoids. The major flavonoid component of MRE was morusin. MRE and morusin inhibited lipopolysaccharide-induced production of nitrite and prostaglandin E2 in RAW264.7 cells. MRE and morusin also suppressed the formation of intracellular reactive oxygen species and the expression of iNOS and COX-2. In an in vivo study, a thiobarbituric acid reactive substances assay showed that MRE inhibited CCl4-induced oxidative stress and expression of nitrotyrosine. MRE also decreased CCl4-induced hepatic iNOS and COX-2 expression, as well as CCl4-induced hepatic inflammation and necrosis in mice. Conclusion: MRE exhibited antiinflammatory and hepatic protective activity