A PILOT STUDY OF BALL IMPACT CHARACTERISTICS IN VARIED BALL LAUNCHED DIRECTIONS IN SOCCER INSTEP KICK

The purpose of the present study was to identify the characteristics of ball impact foot motion in various ball launched directions. Eighteen trials of soccer instep kicking targeting six areas of the full-size soccer goal at 11 m, were analysed. The collision between the foot and ball was recorded using three ultra-high-speed cameras at 2000 Hz. The foot contact point on the ball and the foot swing direction had a strong correlation with the ball launch direction. It can be interpreted that the foot contact point and swing direction are essential factors to kick the ball towards the targeting direction. Moreover, the roll angle of the foot segment significantly affected the ball launch direction. This result suggested that the roll angle has a role in facing the instep of the foot towards the target direction in order to control the ball launch direction

PELVIC ROTATION DYNAMICS OF ACCURACY ENHANCED, SUBMAXIMAL EFFORT INSTEP SOCCER KICKING

The purpose of this study was to clarify the kinetic aspects of the pelvic rotation in accuracy enhanced, submaximal effort soccer instep kicking. Fifteen male soccer players conducted instep kicking in a maximal (MAX) effort and a submaximal (SUB) effort with an emphasis on accuracy. Kicking motions were recorded by a motion capture system with a force platform at 500 Hz. The counter-clockwise pelvic rotation decreased significantly in SUB. Also, the interaction torque on the support leg hip joint decreased significantly in SUB. A previous study reported that the interaction torque was the primary factor in producing pelvic rotation. Thus, controlled pelvic rotation seen in SUB is most likely due to a reduced interaction torque acting on the support leg hip joint. It can be considered that to restrain pelvic rotation is a strategy to slow down the foot swing velocity in accuracy enhanced, submaximal effort instep kicking

HIGH-LOADING ABSORPTION CHARACTERISTICS OF NATURAL AND ARTIFICIAL TURFS

The present study was designed to illustrate shock attenuation characteristics of natural turf as a target property for long pile artificial turf (3-g turf) and to compare the property with that of existing 3-g turf systems. A recently proposed new high loading test was conducted to detect the initial state of shock attenuation property of natural turfs with two different bases (sod and sand base) and of 3-g turfs with three different infills (sand, rubber and sand/rubber). Clear differences between these turfs were observed as the natural turfs are having a higher impact damping and a larger hysteresis with plastic surface deformation. Those features would be beneficial in lowering a high load imparted to the human body but might limit player’s performance

Chironomid fauna Piptera: Chironomidae) in the Hosomidani valley, western Chugoku Mountains, Japan

The Hosomidani riparian fbrest, located around the origin of the Ohta River basin, is one of the most nature-rich districts in Japan. We investigated chironomid fauna in the Hosomidani valley as　anindicator taxon to evaluate the species diversity of　&eshwater benthic macroinvertebrates. On 23 August and 2 November, 2005, ironomid lalvae were collected in the main stream of the Hosomidani River, small streamletsflowing Into the main stream and the floodplain marsh along the Hosomidani River,and were reared to adults in the laboratory to identify species. A total of 52 species was collected and of which 17 Were newly recorded in the Ohta River basin Thirty-five species were collected in the main stream and of which 14 were also fblmd in the streamiets. On the other hand, 12 out of 16 species collected inthefloodplain marshes were not found in the main streamand streamiets, Polypedilum (Trliodura) caudocula was only found in the noodplain and this is the second record next tothe descnptlOn Of this species in 1991 ･ These results indicate thaHhe high species diversity of cbironomids in tile Hosomidani valley is supported by the presence of the noodplain,Article信州大学山地水環境教育研究センター研究報告 6: 103-108(2010)departmental bulletin pape

BASIC MECHANICAL ANALYSIS OF SOCCER BALL IMPACT

The present study aimed to provide a reference of the nature and the magnitude of the ball reaction force during ball impact. A soccer ball directly fired to the force platform and the sagittal motion was captured at 5000Hz. The peak forces and impulses during ball contact were computed from the displacement of the ball geometric centre (CB force / impulse) and the centre of the gravity (CGB force / impulse), and those values were compared with the force directly measured from the force platform (D force / impulse). Overall, the CGB forces were comparable to the D force while the CB forces were substantially overestimated. Those impulses were well matched with the theoretical value computed from the change of ball momentum before and after the contact. Those findings of the present study confirmed the reliability of the CGB model

ALMA Measurement of 10 kpc-scale Lensing Power Spectra towards the Lensed Quasar MG J0414+0534

We report the first measurement of lensing power spectra for gravitational potential, astrometric shifts, and convergence perturbations towards the anomalous quadruply lensed quasar MG$\,$J0414+0534. To obtain the spectra, we conducted observations of MG$\,$J0414+0534 using the Atacama Large Millimeter/submillimeter Array (ALMA) with high angular resolution (0.02"-0.05"). We developed a new partially non-parametric method in which Fourier coefficients of potential perturbation are adjusted to minimise the difference between linear combinations of weighted mean de-lensed images. Using positions of radio jet components, extended dust emission on scales $>1\,$kpc, and mid-infrared flux ratios, which are microlensing free, our new multi-wavelength method provides us with a very effective tool for probing cosmological matter fluctuations on scales $< 10\,$kpc. Assuming that contributions from structures on angular scales <1.0" are negligible, on an angular scale of $\sim$1.3" (corresponding to an angular wave number of $l \sim 1.1\times 10^6$ or $\sim 8\,$kpc in the lens plane), the measured convergence, astrometric shift, and potential powers are $\varDelta_\kappa=0.021-0.028$, $\varDelta_\alpha =7-9\,$mas, and $\varDelta_\psi=1.2-1.6\,$$\textrm{mas}^2$, respectively. Our result is consistent with the predicted abundance of haloes in the line of sight and subhaloes in cold dark matter models. Our partially non-parametric lens models suggest a presence of a clump in the vicinity of object Y, a possible dusty dwarf galaxy and some small clumps in the vicinity of lensed quadruple images. Although much fainter than the previous report, we confirmed weak continuum emission from object Y with a peak flux of $\sim 100\,\mu \textrm{Jy}\, \textrm{beam} ^{-1}$ at the $\sim 4\,\sigma$ level.Comment: 29 pages, 35 figures, analyses of models with a possible dwarf galaxy, object Y and that of chi^2 fit in the visibility plane were adde

CONTRIBUTION OF THE SUPPORT LEG TO ACCELERATE KICKING LEG SWING DURING SOCCER INSTEP KICKING

The present study aimed to determine the contribution of support leg motion to the acceleration of the kicking leg in soccer instep kicking. The kicking motion was recorded by a motion capture system. According to the procedures proposed in previous studies, the power due to the muscle and interaction moments acting on the kicking lower leg was computed. The forward swing of the lower leg during the final phase of kicking was dominated by the power of the interaction moment rather than by that of the muscle moment. The support leg motion contributed to produce more than 50 % of the total amount of positive work due to the power of the interaction moment. The present study proposed a reasonable mechanism for the acceleration of the lower leg swing when its angular velocity exceeds the inherent force-velocity limitation of muscles