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The first inter-calibration study of the stable silicon isotope composition of dissolved silicic acid in seawater, δ 30 Si(OH) 4, is presented as a contribution to the international GEOTRACES program. Eleven laboratories from seven countries analyzed two seawater samples from the north Pacific subtropical gyre (Station ALOHA) collected at 300 m and at 1000(More)
  • Z Cao, L Qian
  • 1997
This study examined the effects of focal point displacement on image quality in cone beam single photon emission computed tomography (SPECT). A new image reconstruction algorithm that accounts for the focal point shift was derived and three shift geometries were investigated. The geometries included a lateral shift with a fixed focal length but off-center(More)
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