Search

Introduction: In this study, we evaluated the differences and measurement accuracy in the force–displacement relationship of the distal radioulnar joint (DRUJ) between patients with triangular fibrocartilage complex (TFCC) injury and healthy controls using force-monitor ultrasonography. Methods: This study included 11 TFCC injury patients and 22 healthy controls. We evaluated differences in the force–displacement relationship of the DRUJ in these patients using force-monitor ultrasonography. Cyclic compression was applied to the dorsal surface of the ulnar head. Distance between the dorsal surface of the distal radius and ulnar head at the DRUJ level was measured in the initial and pressed-down positions. Changes in radioulnar displacement, applied force, and displacement-to-force ratio were measured. Furthermore, we compared the parameters between the affected and unaffected wrists and between TFCC injury patients and controls. Results: The radioulnar displacement and displacement-to-force ratio were significantly larger in the affected wrists than in the unaffected wrists (P = 0.003 and P = 0.02). The affected/unaffected side ratio of radioulnar displacement and displacement-to-force ratio were significantly larger in the TFCC injury patients than in the controls (P = 0.003 and P = 0.02). The area under the curve was 0.82 for the affected/unaffected ratio of the radioulnar displacement. The optimal cutoff value indicated by the receiver-operating characteristic curve for the affected/unaffected ratio of the radioulnar displacement was 1.71; the sensitivity and specificity were 82% and 86%, respectively. Conclusions: Assessing the DRUJ instability with force-monitor ultrasonography may help identify TFCC-injured wrists. [ABSTRACT FROM AUTHOR]

Purpose: To test the concurrent validity of data from 2 different global positioning system (GPS) units for obtaining mechanical properties during sprint acceleration using a field method recently validated by Samozino et al. Methods: Thirty-two athletes performed maximal straight-line sprints, and their running speed was simultaneously measured by GPS units (sampling rate: 20 or 5 Hz) and either a radar or laser device (devices taken as references). Lower-limb mechanical properties of sprint acceleration (theoretical maximal force, theoretical maximal speed, maximal power) were derived from a modeling of the speed-time curves using an exponential function in both measurements. Comparisons of mechanical properties from 20- and 5-Hz GPS units with those from reference devices were performed for 80 and 62 trials, respectively. Results: The percentage bias showed a wide range of overestimation or underestimation for both systems (-7.9% to 9.7% and -5.1% to 2.9% for 20- and 5-Hz GPS), while the ranges of its 90% confidence limits for 20-Hz GPS were markedly smaller than those for 5-Hz GPS. These results were supported by the correlation analyses. Conclusions: Overall, the concurrent validity for all variables derived from 20-Hz GPS measurements was better than that obtained from the 5-Hz GPS units. However, in the current state of GPS devices' accuracy for speed-time measurements over a maximal sprint acceleration, it is recommended that radar, laser devices, and timing gates remain the reference methods for implementing the computations of Samozino et al. [ABSTRACT FROM AUTHOR]

Nine toroidal field (TF) coils have been developed in Japan for the international thermonuclear experimental reactor (ITER). The joint resistance of TF coil should satisfy the requirement of smaller than 3 nano-ohm at 2 T of external magnetic field and 68 kA of transport current. Full-size joint sample (FSJS) tests were performed for joint development and for TF coil manufacture, as part of the process control. 11 FSJS tests are conducted in total. FSJS tests were conducted with assistance from a test faculty in the National Institute for Fusion Science as reported in a previous paper. All FSJS tests successfully satisfied the requirement of resistance less than 3 nΩ at 2 T. Additionally, the TF coil joints are subjected to cyclic electromagnetic force and warm-up/cool-down during the ITER operation. The authors investigated the joint performance for the abovementioned influence. The results showed no degradation in the joint resistance. Thus, the TF joint developed in Japan was qualified successfully. [ABSTRACT FROM AUTHOR]

This study aims to elucidate whether the force applied by an infant's tongue differs or not depending on geometrical differences in the artificial nipples. We developed three sensorized artificial nipple devices using six small force sensors and we have measured the tongue force during sucking in 11 infants. As a result, we have showed that the order of sensor responses and sucking period are similar among different geometries of artificial nipples. However, we have also observed that the maximum force measured differed in different artificial nipples. Furthermore, we have also observed differences in the estimated velocity the tongue movement between individual infants. Overall, this study showed that it is feasible to measure the dynamic properties of artificial nipples toward the definition of clear recommendations for mothers that wish to select the appropriate artificial nipple for their babies on an individual basis. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

For the accurate measurement of small masses and forces, a voltage balance that uses electrostatic force between electrodes has been developed at the National Metrology Institute of Japan (NMIJ). This voltage balance enables traceable mass and force measurements based on the revised definition of the kilogram, as per electric standards. To confirm the reliability of the developed balance apparatus, the mass of a 2 mg wire weight was determined. The first complete uncertainty analyses were performed, following which the relative standard uncertainty of the mass measurement was estimated to be $5.3 \times 10^{-4}$. The mass of the weight was measured via the submultiple method in a traceable manner with respect to the mass standard at NMIJ. The results obtained from the two different methods were observed to be in agreement within their uncertainties. [ABSTRACT FROM AUTHOR]

Background: During pitching, an overloaded joint reaction force exerted on the shoulder and excessive shoulder horizontal abduction at ball release are considered risk factors causing anterior shoulder pain for young baseball pitchers. Hypothesis/Purpose: The first aim was to examine the relationship between shoulder horizontal abduction position and force on the shoulder at ball release. The second was to identify the relative rotational position of the shoulder and the range of shoulder motion at ball release that minimize force on the shoulder. It was hypothesized that the amount of force on the shoulder would be exacerbated by excessive shoulder horizontal abduction. Study Design: Descriptive laboratory study. Methods: Participants were 183 adolescent baseball pitchers (mean ± SD age, 15.5 ± 1.2 years) without shoulder/elbow problems. Each pitcher threw 5 fastballs to a catcher behind a home plate. The kinematics and kinetics of the throwing shoulder during fastball pitching were calculated with 3-dimensional measurements from 36 reflective markers. In data analysis, the correlations were calculated between the relative rotational positions of the shoulder (abduction, horizontal adduction-abduction) and the forces on the shoulder (anterior-posterior, proximal, and superior-inferior) at ball release. Subsequently, the specific rotational position and range of motion of the shoulder at ball release that minimized forces on the shoulder were determined. Results: Statistically significant correlations were identified between the magnitude of superior-inferior force on the shoulder and shoulder abduction position (R2 = 0.44, P < .001) as well as between the magnitude of anterior-posterior force on the shoulder and shoulder horizontal adduction-abduction position (R2 = 0.72, P < .001). Minimal anterior-posterior and superior-inferior forces were obtained with a combination of 80.6° of shoulder abduction and 10.7° of shoulder horizontal adduction. Any deviation >5° from this position significantly increased the anterior-posterior and superior-inferior forces on the shoulder. Conclusion: Increasing shoulder horizontal abduction position significantly increased the magnitude of anterior force on the shoulder at ball release. The combination of 80.6° of shoulder abduction and 10.7° of horizontal shoulder adduction minimized the shear forces on the shoulder at this point. Clinical Relevance: The present data can be useful for screening pitching technique to prevent shoulder pain and injury with motion capture assessment. [ABSTRACT FROM AUTHOR]

The 2004 Indian Ocean tsunami and the recent 2011 Japan tsunami have highlighted the need to investigate the interaction between tsunamis and coastal structures. Although some efforts have been made to determine tsunami loads on structures, there are discrepancies between the limited number of published design guidelines. This study comprises an experimental investigation of a tsunami bore interaction with an inland structure. Physical modelling of the tsunami bore in the laboratory allowed study of the impact of tsunami bores on a square prism model having different orientations to the flow direction. The use of common geometrical shapes simplifies experiments and increases the reliability of results. The experiments were conducted in a 14 m long, 1.2 m wide and 0.8 m deep wave flume equipped with an automatic gate designed to generate a tsunami bore. Measurements were made of the forces and pressures exerted on the model structure and of the bore heights and velocities. The vertical pressure distribution was measured on what was initially the structure's front wall, with the front wall at 0°, 30°, 45°, 60°, 90° and 135° to its original alignment. A relation between bore velocity and bore height is presented. The measured maximum forces in the stream-wise and upward directions were numerically modelled successfully, and relevant drag coefficients were determined for the structure at different orientations. [ABSTRACT FROM AUTHOR]

Tsunamis in Indonesia (2004) and Japan (2011) severely affected communities bordering the Indian Ocean and Japan's east coast. Despite the plausible findings arising from the available studies, the research on the impact of tsunami bore forces applied to bridges of different designs is limited. This is because the estimation methods for tsunami-induced loads presented in the literature have mainly been developed for buildings and require careful adaptation to apply to bridges. The main focus of the present study is to experimentally examine the interaction between a tsunami bore and a box section bridge with different orientations to the direction of the incoming bore, bore strengths, and deck clearances. The experiments were conducted in a 15-m-long, 1.2-m-wide, and 1.2-m-deep wave flume. The forces and pressures applied to the bridge, the bore heights, and the velocities were measured. It was found that the skewed bridge deck is subjected to additional force and moment components, namely the cross-stream force (F y) and the rolling and yawing moments (M x and M z). These components are non-existent for the unskewed bridge deck. Based on the experimental results, equations were proposed for estimating tsunami forces for a box section bridge deck. • Two main stages were observed during the impact of a tsunami bore on a bridge deck: 1) initial impact, and 2) fully inundated condition. • The streamwise force applied to a bridge deck is mainly correlated with the tsunami bore flow velocity. • A different impact mechanism was observed for a skewed bridge deck, creating the lateral force (F y) and the rolling and yawing moments (M x and M z). • The results show a decreasing trend for the streamwise and vertical tsunami forces and pitching moments as the skew angle increased. • Mathematical formulations based on the experimental results were developed for estimating the tsunami-induced forces on bridge decks with different skew angles. [ABSTRACT FROM AUTHOR]