掺Yb^3＋的氧化镧钇透明激光陶瓷的光谱特性

采用传统陶瓷烧结工艺，在无压还原气氛中低温制备了Yb^3＋掺杂量高达10％（按摩尔计）的透明性良好的氧化镧钇激光陶瓷，研究了其在室温的吸收光谱、发射光谱以及荧光寿命。结果表明：掺Yb^3＋氧化镧钇透明激光陶瓷具有宽的吸收和发射光谱以及长的荧光寿命。吸收峰位于902，942nm和968nm处，吸收截面分别为0.31×10^-20,0.45×10^-20cm^2和0.53×10^-20cm2：主发射峰位于1032nm和1075nm处，发射截面分别为1.05×10^-20cm^2和0.87×10^-20cm ^

Offshore Migratory Corridors and Aerial Photogrammetric Body Length Comparisons of Southbound Gray Whales, Eschrichtius robustus, in the Southern California Bight, 1988–1990

Through most of their annual migration, gray whales, Eschrichtius robustus, remain within 10 km of shore, but in the Southern California Bight many individuals migrate much farther from shore. This paper summarizes aerial survey and photogrammetric efforts to determine body lengths and temporal and spatial distributions of migratory gray whales in the southern portion of the Southern California Bight. Aerial surveys were flown along 13 east–west transects between lat. 32°35′N and 33°30′N during the southbound gray whale migratory seasons of 1988–90 in the Southern California Bight. Photogrammetry was used to obtain body length estimates of animals during some of the surveys. A total of 1,878 whales in 675 groups were sighted along 25,440 km of transect distance flown and 217 body lengths were measured. Using position and heading data, three major migratory pathways or corridors in the southern portion of the bight are defined. Those migrating offshore were split almost evenly between two corridors along the west sides of Santa Catalina and San Clemente Islands. These corridors converge on the mainland coast between San Diego and the United States–Mexico border. No whales larger than 11.5 m were photographed within 30 km of the mainland coast, suggesting that smaller, and presumably younger, whales use the coastal migratory corridor through the California Bight.

Restormel Fish Counter Annual Report 2011

This is the Restormel Fish Counter, Annual Report 2011 produced by the Environment Agency, Environmental Monitoring Team on May 2012. The report presents the upstream counts of migratory salmonids recorded on the River Fowey at Restormel Weir fish counting station (SX 107 613) over the period March 2011 to February 2012 inclusive. The minimum upstream salmon estimate for 2011, over the period July 2011 to February 2012, was 675. The minimum upstream sea trout estimate for 2011 was 10,022, which is the fifth highest count recorded in the last 17 years. The fish counter at Restormel had six periods of downtime due to counter faults which equated to 19 days of downtime overall. Fish counts were estimated for downtime caused by counter faults but not for weir cleaning due to the small numbers of fish involved.