Angular momentum in skilled kicking pullover performed by elementary school children

Topics in Exercise Science and Kinesiology Volume 3: Issue 1, Article 2, 2022. This study aimed to clarify the differences in body positions and the role of the swing leg, support leg, and head-arm-trunk segment in generating and maintaining angular momentum of the whole body about a horizontal bar as well as how to improve the skill level of successful kicking pullover attempts. Two-dimensional kinematic parameters of successful kicking pullover attempts and body composition indices of 26 fifth-grade elementary school children were collected. Their techniques were classified into excellent and good groups based on the subjective evaluation of three evaluators. Although there were no significant differences in body composition indices between the two groups, the motion phase time during the 4th phase and the total time of the excellent group were significantly shorter compared with the good group. Also, the counterclockwise rotation of the angular momentum of the head-arm-trunk segment and the whole body during the 4th phase was significantly larger in the excellent group than in the good group. These results suggest that maintaining the angular momentum of the head-arm-trunk segment during the 4th phase leads to attempts with shorter time and improves skill levels from the good group to the excellent group. The good group was not able to maintain angular momentum of the whole body during the 4th phase because the peak of the angular momentum of the head-arm-trunk segment and support leg tended to appear earlier than in the excellent group. we newly clarified that teachers need to focus on the body position of the trunk and head during the 4th phase in order for elementary school children to succeed in kicking pullovers more beautifully at a higher level

Suppressive effect of azithromycin on Plasmodium berghei mosquito stage development and apicoplast replication

<p>Abstract</p> <p>Background</p> <p>Azithromycin (AZM) is a macrolide antibiotic that displays an excellent safety profile even in children and pregnant women and has been shown to have anti-malarial activity against blood stage <it>Plasmodium falciparum</it>. This study evaluated the transmission-blocking effect of AZM using a rodent malaria model.</p> <p>Methods</p> <p>AZM-treated mice infected with <it>Plasmodium berghei </it>were exposed to <it>Anopheles stephensi </it>mosquitoes, followed by the observation of parasite development at different phases in the mosquito, i.e., ookinetes in the midgut, oocysts on the midgut, and sporozoites in the midgut and salivary glands. Furthermore, to evaluate the effect on organelle replication of each stage, quantitative real-time PCR analysis was performed.</p> <p>Results</p> <p>The inhibitory effect of AZM was noticeable in both gametocyte-ookinete transformation in the midgut and sporozoite production in the oocyst, while the latter was most remarkable among all the developmental phases examined. Real-time PCR analysis revealed that AZM suppressed apicoplast replication at the period of sporozoite production in oocysts.</p> <p>Conclusions</p> <p>AZM inhibits parasite development in the mosquito stage, probably through the same mechanism as in the liver and blood stages. Such a multi-targeting anti-malarial, along with its safety, would be ideal for mass drug administration in malaria control programmes.</p

On the Characteristic Difference of Neoclassical Bootstrap Current and Its Effects on MHD Equilibria between CHS Heliotron/Torsatron and CHS-qa Quasi-Axisymmetric Stellarator

The characteristic difference of neoclassical bootstrap current and its effects on MHD equilibria are described for the CHS heliotron/torsatron and the CHS-qa quasi-axisymmetric stellarator. The direction of bootstrap current strongly depends on collisionality in CHS, whereas it does not in CHS-qa because of quasi-axisymmetry. In the CHS configuration, it appears that enhanced bumpy (Bs1) and sideband components of helical ripple (By1) play an important role in reducing the magnetic geometrical factor, which is a key factor in evaluating the value of bootstrap cuffent, and determining its polarity. The bootstrap current in CHS-qa is theoretically predicted to be larger than that in CHS and produces significant effects on the resulting rotational transform and magnetic shear. In the finite B plasmas, the magnetic well becomes deeper in both CHS and CHS-qa and its region is expanded in CHS. The existence of co-flowing bootstrap current makes the magnetic well shallow in comparison with that in currentless equilibrium

Orbit Topology and Confinement of Energetic Ions in the CHS-qa Quasi-Axisymmetric Stellarator

The orbit topology and confinement of neutral beam-injected energetic ions are investigated for the current target configuration of the CHS-qa quasi-axisymmetric stellarator. It was shown that tangentially co-injected neutral beam (NB) heating is efficient even at a low magnetic field strength Bt of 0.5 T, whereas the heating efficiency of the counter-injected NB becomes significantly lower as Bt decreases because of the increase of first orbit loss. The energy loss rate increases as the beam injection angle becomes perpendicular, suggesting that the residual non-axisymmetric ripple in the peripheral domain plays a role in enhancing the transport of trapped ions. An interesting observation involves the appearance of the island structure in both the gyro motion following orbit and the guiding center collisionless orbit of counter-moving transit beam ions. It appears under a particular, narrow range of parameters, i.e., energy, pitch angle v///v, normalized minor radius r/a at the launching point and Bt

Effects of Current Profile on Global Ideal MHD Stability in a Compact Quasi-Axisymmetric Stellarator

The global ideal magnetohydrodynamic (MHD) stability for a proposed compact quasi-axisymmetric stellarator CHS-qa has been investigated taking the effect of bootstrap current into account. Assuming experimentally achievable density and temperature profiles, the stability properties of global low-n modes have been studied by using threedimensionalnumerical codes based on fixed boundary MHD equilibria including self-consistent bootstrap current for the CHS-qa reference configuration. Consequently it has been shown that values of edge rotational transform play a crucial role in triggering external kink instability. Concerning a lot of other possibilities in experimental practice to change the total parallel current, we have also studied equilibria with increased or decreased parallel current, but fixed profile. The onset of external kink modes depends on rotational transform or current profile, and we found a stable equilibrium in spite of the edge rotational transform above 0.5. The results imply the possibility of stabilizing external kink modes through current and/or pressure profile control in high beta equilibria