Tennis Racket Research Articles

The discovery of a new type of innervation in lymphoid organs.

It is well known that the main forms of innervation are synapses and free nerve endings, while other forms of innervation have not been reported. Here, we explore a new way of innervating lymphoid organs. Male Sprague-Dawley rats were used for studying the innervation of sympathetic nerve fibers in lymph nodes by means of anterograde tracking, immunoelectron microscopy, three-dimension reconstruction analysis, and immunofluorescence labeling. The results showed that the Fluoro-Ruby labeled nerve endings targeted only a group of cells in the lymph nodes and entered the cells through the plasma membrane. The electron microscopy showed that the biotinylated glucan amine reaction elements were distributed in the cytoplasm, and most of the biotinylated glucan amine active elements were concentrated on the microtubule and microfilament walls. Birbeck particles with rod-shaped and/or tennis racket like structures can be seen in the labeled cells at high magnification, and Birbeck particles contain biotinylated glucan amine-reactive elements. The immunofluoresence results showed that the Fluoro-Ruby-labeled nerve innervating cells expressed CD207 and CD1a protein. This result confirmed that the labeled cells were Langerhans cells. Our findings suggested that Langerhans cells might serve as a "bridge cell" for neuroimmune cross-talking in lymph organs, which play an important role in transmitting signals of the nervous system to immune system. This study also opened up a new way for further study of immune regulation mechanism.

Surgical Strategies for Partial Breast Reconstruction in Medial-Located Breast Cancer: A 12-Year Experience.

Partial breast reconstruction is challenging in medially located breast cancer, particularly in terms of achieving satisfactory aesthetic coverage. Thus, we aimed to investigate surgical strategies for filling medial defects resulting from breast-conserving surgery to improve patient satisfaction and aesthetic outcomes. We retrospectively evaluated 113 patients (114 cases) with medially located breast cancer between 2007 and 2018. We analysed the patient data, such as breast size, specimen weight, complications, and aesthetic results obtained using a questionnaire. The mean body mass index and specimen weight were 23.43 kg/m² (range, 18.5-26.8) and 83.29 g (range, 15-290 g), respectively. The tennis racket and round-block techniques were chosen for small defects (< 10%-15%) in small- and medium-sized breasts. The rotational and perforator flap techniques were used for medium-sized defects. The latissimus dorsi (LD) flap technique was used for large defects (> 30%). Hematoma was found in 1 case (0.96%), linear skin necrosis was found in 1 case (0.96%), seroma in the LD flaps was found in 8 cases (7.69%); fat necrosis in the rotational flaps was found in 2 cases (1.92%); and fat necrosis in an anterior intercostal artery perforator flap was found in 1 case (0.96%). 91 patients (87.5%) were satisfied with the aesthetic results. The techniques used in this study for medially located breast cancer can produce fine aesthetic outcomes with regard to breast size and resection volume, with few complications.

테니스라켓 브랜드이미지-자아이미지일치성과 기능적일치성, 브랜드신뢰, 브랜드태도 및 재구매의도의 구조적 관계

Purpose: The purpose of this study is to investigate the effect of tennis racket brand image and consumer self-image congruence on functional congruity, brand trust, attitude toward brand and repurchase intention.BR Method: In order to accomplish the purpose of the study, we selected a sample population of male and female subjects who were over 20 years old who were tennis club members living in C-city and A-city, South Chungcheong Province. Sampling was conducted from January 19th to February 24th, 2019 for a total of 300 people who had experienced purchasing tennis rackets. As a sampling method, convenience sampling method was used and a self-administration method was used, which is a method for respondents to read and answer questions themselves. A total of 280 copies of the collected data were used as final validity samples, except for 20 copies which were deemed inadequate to be appropriate for the purposes of the data. Data processing was done using SPSSWIN Ver. 23.0 and AMOS Ver. 18.0 and after verifying the fit of the model, individual hypotheses were verified. The results of the study are as follows.BR Results: First, actual self-image congruence, which is one of the subfactors of brand image and self-image congruence in tennis racket, had a positive effect on functional congruity. Second, actual self-image congruence, which is one of the subfactors of brand image and self-image congruence in tennis racket, had a positive effect on brand trust. Third, functional congruity had a positive effect on brand trust. Fourth, functional congruity had a positive effect on attitude toward brand. Fifth, functional congruity had a positive effect on repurchase intention. Sixth, brand trust had a positive effect on attitude toward brand. Seventh, brand trust had a positive effect on repurchase intention. Eighth, attitude toward brand had a positive effect on repurchase intention.BR Conclusion: The result shows that the brand image and consumer self-image congruence in the tennis racket affect the repurchase intention through the structural relationship with functional congruity, brand trust, and attitude toward brand.

Frederick W. Taylor and the congruence of active leisure & work

ABSTRACT This article, through the use of a case study focused on Frederick W. Taylor, shows how the issue of mastery with people engaged in their work can be a significant factor connecting a person’s work and leisure worlds. As a labourer, then gang boss in a steel mill, Taylor “developed” stratagems piecemeal to solve the problems that he faced in working in industrial factories. The issue of time became fundamental in his thinking and led to his becoming a manager and “The father of Scientific Work Management”. Concurrently his leisure pursuits grew from nightly runs to becoming a champion tennis player, to becoming an Olympic golfer, to fashioning his own tennis racket and golf clubs while experimenting over years with many varieties of seeds in an attempt to create “the one best” type of grass for putting greens. His work life never stopped. There is not time and then spare time, J. B. Priestley wrote and Taylor became adept at “Managing all his Time”. His life experience may be seen as an illustrative case of how work (of an engaged nature) and what mindset one comes to embrace at work can be replicated in one’s leisure time physical activities.

Trajal Harrell: The Anxiety of Autobiography

Trajal Harrell: The Anxiety of Autobiography

Supraglottic Airways, Tennis, and Neonatal Resuscitation.

Supraglottic Airways, Tennis, and Neonatal Resuscitation.

The Approximate Solution of Nonlinear Vibration of Tennis Based on Nonlinear Vibration Differential Equation

Abstract In this paper, a nonlinear vibration differential equation is established for the moment when a tennis racket hits the ball. At the same time, we deduce the relationship between the tennis racket string tension and the separation time and distance of the hitting speed. Then the article analyzes the vibration equation of the tennis racket damping ball. We use ANSYS finite element analysis software for solid modeling and modal analysis of tennis rackets. The natural frequency of the tennis racket was obtained through the verification results of the experimental modal analysis. A qualitative relationship between the natural frequency of the vibration-absorbing ball system and some parameters was found.

A newly developed hand rim for wheelchair tennis improves propulsion technique and efficiency in able-bodied novices

A new wheelchair tennis hand rim was developed, having a larger contact area and higher friction. How does this new hand rim compare to a regular hand rim regarding submaximal propulsion with a tennis racket during practice in novices? Twenty-four able-bodied novices (12 Regular Rim, 12 New Rim) completed a one-day experiment: pre-test, three practice-sessions and a post-test of 3 × 4 min each on a wheelchair ergometer (1.11 m/s, 7W). The New Rim group compared to the Regular Rim group, had a lower negative work per cycle (−0.83J vs. −2.06J, p = 0.01) at the post-test. There was a significantly larger increase in mechanical efficiency between the pre- and post-test in the New Rim group (2.3–3.4% vs. 2.1–2.5%, p = 0.02) compared to the Regular Rim group. The new rim led to a more ergonomic propulsion technique, with a reduction in negative power and higher mechanical efficiency between the pre- and post-test at submaximal propulsion.

MEMS Sensors in Tennis Teaching and Training under the Background of Big Data Intelligent Communication

Racket sports (tennis, pawns, tennis, etc.) are currently very popular sports, and they are a very intense aerobic exercise. The climatic conditions of the competition venue, time difference factors, the size of the competition venue, background, lighting, wind direction, etc. may all have an impact on the performance of the game. In order to fully control and eliminate these risk factors, it is recommended to go to the competition site for adaptive training one month in advance. If you can participate in the prematch training camp organized by the general administration, it is of course the best choice. This research mainly discusses the development of MEMS sensors in tennis teaching and training under the background of big data intelligent communication. Using a single inertial sensor fixed on the bottom of the racket for data collection, a real-time data stream window segmentation method based on the combination of sliding window and action window is proposed. Finally, based on the above recognition method, an intelligent tennis training system software is developed, introduces the processing flow of MEMS sensor data, and gives a specific implementation plan for data preprocessing through in-depth study of the characteristics of inertial navigation data. The tennis training system collects the raw data of tennis players during the training process through the MEMS sensor hardware module placed at the bottom of the tennis racket handle, and the sensor module can upload these raw data to the smart phone terminal through wireless communication. The smart phone terminal can analyze and process the collected raw data and finally feedback the number and proportion of each technical action of the tennis player in the training process and the maximum racquet speed through the mobile phone software in real time. After the practice training, the average CTN score of the control group was 141.73, and the standard deviation of the data was 4.185. After the practice training, the average CTN score of the experimental group was 161.67, and the standard deviation was 6.042. This research will improve the efficiency of tennis teaching and training.

Research on Optimal Control Method of Tennis Racket String Diameter Based on Kalman Filter Algorithm

In order to explore the optimal control method of tennis racket string diameter, this paper applies the Kalman filter algorithm to the collection and processing of tennis sports parameters. When the Kalman filter uses the optimal gain (the Kalman filter enters the steady state), the corresponding cost function is established based on the noncorrelated nature of its residual sequence, which is used as the judgment condition for the sampling strategy switch to improve the stability of the system. In addition, this paper improves the real-time performance and calculation accuracy of data transformation through adaptive sampling strategy and adaptive scale factor, improves the stability and estimation accuracy of the system as a whole, and builds an intelligent monitoring system. Finally, this paper systematically studied the optimization control method of tennis racket string diameter and verified that the Kalman filter algorithm can play a certain role in the optimization control of tennis racket string diameter.

수정 IPA를 이용한 테니스 동호인의 라켓 구매 시 선택속성 분석

Purpose: This study aims to use importance-performance analysis (IPA) of selection attributes in a tennis club member’s purchase to derive the ranking of priority for items that need improvement, to provide basic data that can later be used by businesses related to tennis products or tennis supply stores to efficiently determine or apply marketing strategies.BR Method: A survey was done with 370 tennis club members who play in Psuan tennis clubs. 348 surveys were used in the actual analysis, excluding 22 surveys that weer deemed to be incomplete or not properly done. For data analysis, SPSS Win Ver 26.0 program was used with a statistical significance level set at α.05. To certify the validity and credibility of the survey, factor analysis were done and produced a coefficient of Cronbach’s α. To draw the study result, analysis of frequency, exploratory factor analysis, paired-samples t-test, and revised IPA have been done.BR Results: The findings of the study are as follows. First, when purchasing a tennis racket, the importance ranking for the selection attributes was in the order of weigh, tease of use of technology, and durability. The ranking of achievement was in the order of imported brand, bradn awareness, and luxury brand. Second, as a result of analyzing the difference between the importance and achievement of the selection attribute when purchasing a tennis racquet, it was found that there was a significant difference in all questions except for ‘color’ and ‘shape’ of the design factor. Third, In the Ⅰ quadrant, seven items were included, including ‘weight’, and ‘shape’, In the Ⅱ quadrant, four items were included, including ‘price discount’, and ‘A/S expertise.’ In the Ⅲ quadrant, six items were included, including ‘A/S accessibility’, and ‘A/S period’, In the Ⅳ quadrant, five items were included, including ‘design’, and ‘color.’BR Conclusion: In summary, it is judged that it is necessary to establish a marketing strategy for the selective attributes included in Quadrant II, which are considered important by tennis club members, but with low achievement, and to derive improvement measures to improve the performance.

FACTORIAL VALIDITY AND RELIABILITY OF AGILITY TEST OF NON-SPECIFIC AND SPECIFIC PRE-PLANNED FOR THE ATHLETE OF YOGYAKARTA, INDONESIA

Agility is the most important aspect in the tennis court to support the athlete’s performance, but there is a study focusing on the performance applying of agility especially for tennis and comparing it with the performance of non-specific agility which is equal. The aim of this research is to evaluate the factorial validity and reliability of the three agility tests which have been planned, conducted in the condition (with a tennis racket) and non-specific (without a tennis racket). The sample consists of 28 tennis players (15 males and 13 females; age 17 ± 1 year and 16 ± 1,2 years; height 160 ± 30 cm and 168 ± 7 cm, bodyweight 50 ± 5 kg and 52 ± 7 kg). The variable consists of three agility tests such as the 20-yard test, T-test and Illinois test, all tests were conducted with and without a racket. The reliability among and in the subjects was found high (Cronbach Alpha: 0,92 to 0,98; variation coefficient: 3 to 8 percent), with the reliability and stability for specific measurement. The correlation of non-specific and specific agility performance was high (≥0,83), meanwhile for factor analysis only one which was significant according to Guttman-Kaiser. The 20-yard test result was better when the test was conducted in certain conditions (T-test = 2,65; p &amp;lt;0,05). For the Illinois test, the good result was in non-specific condition (uji-t = 2,95; p &amp;lt;0,05), which was conducted with the duration 20 seconds and conducted in non-specific. The result of the test showed that the athlete having good agility will make the performance and pattern of playing to be maximal as well as support the athlete’s prestige. In this founding, when conducting the agility test of pre-planned especially for tennis, it is suggested to use the test having a short duration which is less than 10 seconds and specific sport kind which is corresponding with the sport to conduct the measurement of agility.&lt;p&gt; &lt;/p&gt;&lt;p&gt;&lt;strong&gt; Article visualizations:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;img src="/-counters-/edu_01/0923/a.php" alt="Hit counter" /&gt;&lt;/p&gt;

A Novel Artificial Neural Network-Based Biomechanical Research on Elbow Injury of Tennis Serve

Tennis is a sport with a large age span. Its technology is complex. Factors such as tennis racket and service position will affect the effect of players holding the ball, but often the service posture and strength will affect the players’ elbow tendon. Once the service posture is wrong or the strength is too strong, it will cause irreversible damage to players. Therefore, the study of artificial neural network training on tennis elbow injury is of great significance. Based on artificial neural network, this paper studies the biomechanics of elbow injury in tennis service. Firstly, this paper expounds the concept and characteristics of tennis service technology and studies the injury of tennis players’ elbow. Then this paper studies the artificial neural network technology and uses the experimental comparison method to test the force generated by the two groups of tennis players from different angles. The results show that, in the professional group, the forearm is in the internal rotation state before and after hitting the ball, while the beginner group is generally in the external rotation state. It can be inferred that, under the constant collision force, the reversal force absorbed by the beginner group in the swing process is greater than that of the professional group, which will increase the load of the supinator muscle on the antipronation, which will damage the supinator muscle, which is also one of the causes of the “tennis elbow” disease.

First Characterization of a Hafnia Phage Reveals Extraordinarily Large Burst Size and Unusual Plaque Polymorphism.

A unique lytic phage infecting Hafnia paralvei was isolated and identified. Hafnia phage Ca belongs to the family Autographiviridae, possessing an icosahedral head with a diameter of 55 nm and a short non-contractile tail. Unusually, the burst size of Hafnia phage Ca of 10,292 ± 1,097 plaque-forming units (PFUs)/cell is much larger than other dsDNA phages reported before. Compared to the genome of the related phage, Hafnia phage Ca genome contains extra genes including DNA mimic ocr, dGTP triphosphohydrolase inhibitor, endonuclease, endonuclease VII, and HNH homing endonuclease gene. Extraordinarily, the phage developed different sizes of plaques when a single plaque was picked out and inoculated on a double-layer Luria broth agar plate with its host. Furthermore, varied packaging tightness for the tails of Hafnia phage Ca was observed (tail length: 4.35–45.92 nm). Most of the tails appeared to be like a cone with appendages, some were dot-like, bun-like, table tennis racket handle-like, and ponytail-like. Although the complete genome of Hafnia phage Ca is 40,286 bp, an incomplete genome with a deletion of a 397-bp fragment, containing one ORF predicted as HNH homing endonuclease gene (HEG), was also found by high throughput sequencing. Most of the genome of the virus particles in large plaques is complete (>98%), while most of the genome of the virus particles in small plaques is incomplete (>98%), and the abundance of both of them in medium-sized plaques is similar (complete, 40%; incomplete, 60%). In an experiment to see if the phage could be protective to brocade carps intramuscularly injected with H. paralvei LY-23 and phage Ca, the protection rate of Hafnia phage Ca to brocade carp (Cyprinus aka Koi) against H. paralvei was 33.38% (0.01 < p < 0.05). This study highlights some new insights into the peculiar biological and genomic characteristics of phage.

Sprint performance and force application of tennis players during manual wheelchair propulsion with and without holding a tennis racket.

The objective of this exploratory research is to study the impact of holding a tennis racket while propelling a wheelchair on kinetic and temporal parameters in a field-based environment. 13 experienced wheelchair tennis players with disabilities (36.1 ± 8.2 years, 76.8 ± 15.3 kg, 174.8 ± 17.1 cm) classified between 30/8 and first series performed two 20 m sprints in a straight line, on a tennis court: one while holding a tennis racket and the second without a tennis racket. They used their own sports wheelchair. Potential participants were excluded if they had injuries or pain that impaired propulsion. Maximal total force, maximal propulsive moment, rate of rise, maximal power output, push and cycle times and maximal velocity were measured. Sprinting while holding a tennis racket increased the cycle time by 0,051 s and push time by 0,011s. Sprinting while holding a tennis racket decreased the maximal propulsive moment, maximal power output, rate of rise and maximal velocity during propulsion by 6.713 N/m, 151.108 W, 672.500 N/s and 0.429 m/s, respectively. Our results suggest that the biomechanical changes observed associated with racket propulsion are generally in a direction that would be beneficial for the risk of injury. But sprinting holding a racket seems to decrease players propulsion performance. Working on forward accelerations with a tennis racket would be a line of work for coaches.

Dancing pen: The ultimate test of graphically matured skilled writer

Unconscious and automatic rhythmic production of handwriting by graphically matured skilled writers through perfect synchronization of muscular body parts is an activity that resembles a pen dancing on paper, analogous to a dancer performing on stage. This analogy can lead to beginners in the profession better understanding the complex and intricate writing process.&#x0D; There are several routine activities requiring various complex coordinations of mental, sensory, and motor factors by humans, such as walking, talking, writing, dressing, drawing, sewing, using a typewriter, playing a piano or violin, riding a bicycle, driving a car, handling a tool, a tennis racket, or a golf club, etc., which are performed habitually, unconsciously, and automatically once they are learnt and practiced. One of these activities is (hand)writing, which is a complex learned motor behavior generally developed in a person in three stages: formative, impressionable, and graphic maturity. The stage of “graphic maturity” is finally reached when the writing has fully developed, resulting in unique individual characteristics that become habitual in execution, most of which remain relatively constant throughout much of the writer’s active life. The complexities and intricacies of the writing process can be better understood by a beginner in the profession by comparing it with dancing, which is also a similar activity requiring perfect synchronization and coordination of all the body parts involved in the exercise.

Morphometrics for sports mechanics: Showcasing tennis racket shape diversity.

Tennis racket design has changed from its conception in 1874. While we know that modern tennis rackets are lighter and have larger heads than their wooden predecessors, it is unknown how their gross shape has changed specifically. It is also unknown how racket shape is related to factors that influence performance, like the Transverse and Polar moments of inertia. The aim of this study was to quantify how tennis racket shape has changed over time, with a view to furthering our understanding of how such developments have influenced the game. Two-dimensional morphometric analysis was applied to silhouettes extracted from photographs of 514 rackets dating from 1874 to 2017. A principal component analysis was conducted on silhouette outlines, to allow racket shape to be summarised. The rackets were grouped by age and material for further analysis. Principal Component 1 accounted for 87% of the variation in racket shape. A pairwise Pearson’s correlation test indicated that head width and length were both strongly correlated to Principal Component 1 (r = 0.916 & r = 0.801, p-values<0.001). Principal Component 1 was also correlated to the Polar (r = 0.862, p<0.001) and Transverse (r = -0.506, p<0.001) moments of inertia. Racket age and material had a medium (p<0.001, η2p = 0.074) and small (p = 0.015, η2p = 0.017) effect on Principal Component 1, respectively. Mean racket shapes were also generated from the morphometric analyses for the material and age groupings, and we consider how these shape changes may have influenced performance and injury risk. These mean shape groupings could support the development of models, such as finite element analysis, for predicting how historical developments in tennis equipment have affected performance and injury risk.

Smart Table Tennis Racket with Tunable Stiffness for Diverse Play Styles and Unconventional Technique Training (Adv. Mater. Technol. 10/2021)

Smart Table Tennis Racket In article number 2100535, Mengying Zhang, Jinbo Wu, and coworkers invent a smart table tennis racket with tunable stiffness based on electrorheological elastomers. The racket face is a multilayer structure of rubber, soft electrode, anisotropic electrorheological elastomer and copper electrode. By applying an electric field, the smart racket successfully changed the trajectory of balls, reduced ejection angle and increased ejection velocity to adapt to diverse play styles and improve unconventional play technique.

Effect of materials and design on the bending stiffness of tennis rackets

Lawn tennis rackets have changed considerably since the origins of the game. Early rackets were wooden, making them heavier and more flexible than modern designs made from fibre-polymer composites. The fundamental frequency of a freely suspended tennis racket is often used as an analogue to stiffness, despite it being dependent on mass. We estimate the bending stiffness of 525 rackets, dating from 1874 to 2017, using a uniform beam model that accounts for mass. The model suggests composite rackets are typically about twice as stiff as their wooden predecessors. Applying typical values of Young’s modulus, density and second moment of area, the model was used to demonstrate the benefits of fibre-polymer composites for making lightweight, stiff rackets. Undergraduate students could make use of our large dataset of tennis rackets to explore these patterns themselves. They could also go on to measure the dimensions, mass and fundamental frequency of tennis rackets and model them as a uniform beam. Students could also apply the theory to other implements, like badminton and squash rackets or baseball and cricket bats.

Inertial and viscous flywheel sensing of nanoparticles

Rotational dynamics often challenge physical intuition while enabling unique realizations, from the rotor of a gyroscope that maintains its orientation regardless of the outer gimbals, to a tennis racket that rotates around its handle when tossed face-up in the air. In the context of inertial sensing, which can measure mass with atomic precision, rotational dynamics are normally considered a complication hindering measurement interpretation. Here, we exploit the rotational dynamics of a microfluidic device to develop a modality in inertial sensing. Combining theory with experiments, we show that this modality measures the volume of a rigid particle while normally being insensitive to its density. Paradoxically, particle density only emerges when fluid viscosity becomes dominant over inertia. We explain this paradox via a viscosity-driven, hydrodynamic coupling between the fluid and the particle that activates the rotational inertia of the particle, converting it into a ‘viscous flywheel’. This modality now enables the simultaneous measurement of particle volume and mass in fluid, using a single, high-throughput measurement.