A three-dimensional analysis of the contributions of upper limb joint movements to horizontal racket head velocity at ball impact during tennis serving

In this study, we examined the relationship between upper limb joint movements and horizontal racket head velocity to clarify joint movements for developing racket head speed during tennis serving. Sixty-six male tennis players were videotaped at 200 Hz using two high-speed video cameras while hitting high-speed serves. The contributions of each joint rotation to horizontal racket velocity were calculated using vector cross-products between the angular velocity vectors of each joint movement and relative position vectors from each joint to the racket head. Major contributors to horizontal racket head velocity at ball impact were shoulder internal rotation (41.1%) and wrist palmar flexion (31.7%). The contribution of internal rotation showed a significant positive correlation with horizontal racket head velocity at impact (r = 0.490, P < 0.001), while the contribution of palmar flexion showed a significant negative correlation (r = ? 0.431, P < 0.001). The joint movement producing the difference in horizontal racket head velocity between fast and slow servers was shoulder internal rotation, and angular velocity of shoulder internal rotation must be developed to produce a high racket speed.     

A design of fine motion assist equipment for disabled hand in robotic rehabilitation system

This paper reports a newly designed system intended to aid in hand rehabilitation. The motion assistance equipment consists of three parts: mechanisms for the fingers and thumb, a base of these mechanisms, and a motion assistance mechanism for the wrist. The structure of each mechanism is designed to achieve independent, fine motion assistance, especially, for the individual fingers. First, the features of each mechanism in the equipment are explained. Next, the control systems are introduced, which are constructed to realize a self-motion control strategy (i.e., the motion is controlled by its user). Using this control system, the transient response and steady state characteristics of the motion assistance mechanisms for the thumb are evaluated. Consequently, the possibility of practical application is found in regard to some improved points.     

Active recovery effects on local oxygenation level during intensive cycling bouts

We hypothesised that the oxygen supply to the fatigued muscles is improved after the recovery with exercise caused by aerobic metabolism in the slow twitch fibres during the recovery period. Ten males performed a 30 s maximum cycling (1st Exercise), followed by a 20 min rest interval (Interval Rest) in which participants were either sitting (No Exercise) or low intensive cycling (Active). Then they again underwent a 30 s bout of maximum cycling (2nd Exercise). The total work of the 2nd Exercise was higher in Active compared to No Exercise (297 ± 14 vs 276 ± 23 J · kg(-1), P < 0.01). After Interval Rest, the muscle oxygenation level (P < 0.05) and blood lactate concentration (P < 0.05) were lower in Active compared to No Exercise. In Active, the total work was higher in the 2nd Exercise than the 1st Exercise (297 ± 14 vs 277 ± 23 J · kg(-1), P < 0.01), and muscle oxygenation levels during the 2nd Exercise were also higher at 10 (P < 0.05) and 15 (P < 0.01) s after the beginning of the exercise. It was suggested that active recovery exercise would manage to increase the muscle oxygenation level, and improve the performance during the 2nd Exercise accompanied with blood lactate control.     

Cell-enclosing gelatin-based microcapsule production for tissue engineering using a microfluidic flow-focusing system

Gelatin-based microcapsule production using a microfluidic system and the feasibility of the resultant microcapsules for constructing spherical tissues surrounded by heterogeneous cells were studied. The first cell-encapsulation and subsequent cell-enclosing microparticle encapsulation were achieved using a microfluidic flow-focusing droplet production system. A hollow-core structure of about 150 μm in diameter was developed by incubating the resultant microparticles at 37 °C, which induced thermal melting of the enclosed unmodified gelatin microparticles. Mammalian cells filled the hollow-cores after 4 days of incubation. A cell layer on the cell-enclosing microcapsules was developed by simply suspending the microcapsules in medium containing adherent fibroblast cells. This method may prove useful for the generation of gelatin microcapsules using a microfluidic system for formation of artificial tissue constructs.     

Domestic pigeons (Columba livia) discriminate between photographs of male and female pigeons

We investigated whether pigeons are able to discriminate color photographs of male and female pigeons, using a categorical discrimination procedure. In Experiments 1 and 2B, 10 out of 14 pigeons learned the discrimination. Of these, 5 pigeons showed transfer to novel stimuli, demonstrating the categorical nature of the trained discrimination. Experiment 3 showed that the discriminative behavior was based primarily on the body, as opposed to the head and the neck region. In 1 out of 3 pigeons, the discriminative behavior was maintained by the black-and-white photographs. The results suggest that some pigeons have the ability to discriminate the sex of conspecifics without behavioral cues.     

Engineering Play: Children's software and the cultural politics of edutainment

The late 1980s saw the emergence of a new genre of instructional media, ‘edutainment’, which utilized the capabilities of multimedia personal computers to animate software designed to both educate and entertain young children. This paper describes the production of, marketing of and play with edutainment software as a contemporary example of long-standing tensions between the cultural categories of education and entertainment, play and learning. Like prior efforts to wed learning and play, edutainment was founded on the ideal of broadening access to academic learning. Yet, as it became a mainstream commercial enterprise, it was increasingly targeted towards accelerating the achievement of successful children. After first describing the industry and marketing context of edutainment, this paper describes cases of play with edutainment software in an after-school computer club. The analysis utilizes the concepts of “multimedia genre’ and “participation genre” to read across sites of production, distribution and consumption to examine how genres of entertainment, education and edutainment are constituted through the circulation of and play with media artifacts. As in the case of the industry and marketing context, instances of play with edutainment titles follow certain genre conventions of engagement. Titles that are based on academic content and modes of engagement, even with a wrapper of entertainment style, invite a competitive orientation and interaction focused on fulfilling the minimal conditions for moving ahead and getting credit for completion of a task. Unlike more exploratory or construction-oriented software titles, these genres of software are marketed and keyed to the social demands of middle class achievement.     

Kinetics of throwing arm joints and the trunk motion during an overarm distance throw by skilled Japanese elementary school boys

The purpose of this study was to investigate joint kinetics of the throwing arms and role of trunk motion in skilled elementary school boys during an overarm distance throw. Throwing motions of 42 boys from second, fourth, and sixth grade were videotaped with three high-speed cameras operating at 300 fps. Seven skilled boys from each grade were selected on the basis of throwing distance for three-dimensional kinetic analysis. Joint forces, torques, and torque powers of the throwing arm joints were calculated from reconstructed three-dimensional coordinate data smoothed at cut-off frequencies of 10.5–15 Hz and by the inverse dynamics method. Throwing distance and ball velocity significantly increased with school grade. The angular velocity of elbow extension before ball release increased with school grade, although no significant increase between the grades was observed in peak extension torque of elbow joint. The joint torque power of shoulder internal/external rotation tended to increase with school grade. When teaching the overarm throw, elementary school teachers should observe large backward twisting of trunk during the striding phase and should keep in mind that young children, such as second graders (age 8 years), will be unable to effectively utilise shoulder external/internal rotation during the throwing phase.     

The Turner syndrome: cognitive deficits, affective discrimination, and behavior problems

Individuals with sex chromosomal anomalies are known to be at increased risk for learning problems and in some cases social or behavioral problems. Girls with an absent or structurally abnormal second sex chromosome (the Turner syndrome) have been found to have cognitive problem solving deficits and immature, inadequate social relationships. The present study attempted to link cognitive and social problems by assessing the girls' ability to process affective cues. 17 girls with karyotypes consistent with a diagnosis of Turner syndrome were compared to a group of 16 short-stature girls of comparable age, verbal intelligence scores, height, and family socioeconomic status on the Affective Discrimination Task, which required interpretation of affective intention from facial expression. The results revealed that the Turner syndrome girls were less accurate at inferring facial affect than the short-stature controls. Analyses revealed that the Turner syndrome girls performed more poorly on spatial, attentional, and short-term memory cognitive tasks and had more psychosocial problems than the short-stature controls. Ability to discriminate facial affect may be another area of cognitive weakness for girls with the Turner syndrome and may underlie the psychosocial problems found in this sample.     

Effect of terminal locations of pods on biomass production and 13C partitioning in a fasciated stem soybean Shakujo

This study addresses the hypothesis that stagnation of soybean yield on the farm can be improved by selection of a physiological trait favoring carbon assimilate partitioning to terminally placed pods versus genotypes having axillary pods at close plant spacing. ¹³C was fed to source-sink units comprising a leaf, axillary/terminal pods, and petioles at upper and lower positions of the stem axis in two soybean cultivars, namely Shakujo and Enrei, at different densities of populations. The cultivars differ significantly in architecture, Shakujo bearing a few hundreds of pods in close succession to one another in a terminally placed raceme, in contrast to Enrei having axillary racemes. Pod yield per plant was higher in Enrei than in Shakujo at low density, but Shakujo out-yielded Enrei at close spacing. Population density decreased yield per plant and altered the pattern of assimilate partitioning significantly within the plants for both varieties. At high density more assimilates moved to the upper parts at the cost of the lower parts. The terminally placed pods of Shakujo were advantaged to receive assimilates under density stress. No benefit was accrued to pod filling of Enrei, however, under this condition.