Atacama Compact Array Antennas

We report major performance test results of the Atacama Compact Array (ACA) 7-m and 12-m antennas of ALMA (Atacama Large Millimeter/submillimeter Array). The four major performances of the ACA antennas are all-sky pointing (to be not more than 2.0 arcsec), offset pointing (to be < 0.6 arcsec) surface accuracy (< 25(20) micrometer for 12(7)m-antenna), stability of path-length (15 micrometer over 3 min), and high servo capability (6 degrees/s for Azimuth and 3 degrees/s for Elevation). The high performance of the ACA antenna has been extensively evaluated at the Site Erection Facility area at an altitude of about 2900 meters. Test results of pointing performance, surface performance, and fast motion capability are demonstrated.Comment: 3 pages, 2010 Asia-Pacific Radio Science Conference: J2 Millimeter- and Sub-millimeter-wave Telescope and Arra

Effect of resisted sled sprint with different loads on running velocity, step frequency, and step length

It has been shown that training with resistance sled sprints (RSS) can improve running performance, but the effect of different RSS loads on sprint performance is unclear. This study aimed to examine this effect on running velocity, step frequency, and step length. Twenty-one collegiate track and field male athletes (20.6 ± 1.3 years) performed eight 60-m sprints with and without a resisted sled. The sled loads were individually set based on the participant's body mass (BM) and were applied in 10% increments from 20%–80% of BM. A 20-minute rest was allowed between trials. The running distance was divided into six 10-m phases. We analyzed the mean running velocity, step frequency, and step length at each phase, observing significant interactions in each. All indices decreased with increasing loads. Significant differences were observed in running speed and step frequency between all loads, except between 70%–80% of BM, and in the step length between all loads. Additionally, the maximum values for running velocity, step frequency, and length appeared in different phases according to the load. In addition to kinematics, coaches and athletes should focus on setting running distances and loads in RSS training