Based on 310 horizontal-component digital seismograms recorded at 14 seismic stations in Shanxi Digital Seis-mograph Network, the inelastic attenuation coefficient in Shanxi region is studied. By the methods of Atkins...Based on 310 horizontal-component digital seismograms recorded at 14 seismic stations in Shanxi Digital Seis-mograph Network, the inelastic attenuation coefficient in Shanxi region is studied. By the methods of Atkinson and Moya, the site response of each station and several source parameters are obtained and the inversion results from both methods are compared and analyzed. The frequency-dependent inelastic attenuation coefficient Q is estimated as Q( f )=323.2 f 0.506. The site responses of 14 seismic stations do not show significant amplification, which is consistent with their basement on rock. We also found the dependence of corner frequency on seismic moment, seismic moment on stress drop, source radius on stress drop.展开更多
Aims Precipitation pulses and different land use practices(such as grazing)play important roles in regulating soil respiration and carbon balance of semiarid steppe ecosystems in Inner Mongolia.However,the interactive...Aims Precipitation pulses and different land use practices(such as grazing)play important roles in regulating soil respiration and carbon balance of semiarid steppe ecosystems in Inner Mongolia.However,the interactive effects of grazing and rain event magnitude on soil respiration of steppe ecosystems are still unknown.We conducted a manipulative experiment with simulated precipitation pulses in Inner Mongolia steppe to study the possible responses of soil respiration to different precipitation pulse sizes and to examine how grazing may affect the responses of soil respiration to precipitation pulses.Methods Six water treatments with different precipitation pulse sizes(0,5,10,25,50 and 100 mm)were conducted in the ungrazed and grazed sites,respectively.Variation patterns of soil respiration of each treatment were determined continuously after the water addition treatments.Important Findings Rapid and substantial increases in soil respiration occurred 1 day after the water treatments in both sites,and the magnitude and duration of the increase in soil respiration depended on pulse size.Significantly positive relationships between the soil respiration and soil moisture in both sites suggested that soil moisture was the most important factor responsible for soil respiration rate during rain pulse events.The ungrazed site maintained significantly higher soil moisture for a longer time,which was the reason that the soil respiration in the ungrazed site was maintained relatively higher rate and longer period than that in the grazed site after a rain event.The significant exponential relationship between soil temperature and soil respiration was found only in the plots with the high water addition treatments(50 and 100 mm).Lower capacity of soil water holding and lower temperature sensitivity of soil respiration in the grazed site indicated that degraded steppe due to grazing might release less CO_(2) to the atmosphere through soil respiration under future precipitation and temperature scenarios.展开更多
目的探讨Q值调整的个体化切削准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)治疗近视的安全性、有效性、可预测性和稳定性。方法应用美国雷赛Astramax三维角膜地形图仪、Astrapro个体化切削设计程序和Astrascan XL准...目的探讨Q值调整的个体化切削准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)治疗近视的安全性、有效性、可预测性和稳定性。方法应用美国雷赛Astramax三维角膜地形图仪、Astrapro个体化切削设计程序和Astrascan XL准分子激光系统,对33例(66眼)近视患者行Q值调整的个体化LASIK手术。30例(59眼)近视患者作为对照组行标准切削方式的LASIK手术。随访6个月,评价手术疗效。结果标准组和Q值组术后第6个月结果:"!安全性:两组均无一眼下降2行及以上,下降一行的各仅为2眼。"#有效性:术后裸眼视力分别为5.04±0.06和5.05±0.07,5.0以上分别为89.8%和90.9%,5.1以上为49.2%和50.0%。"$可预测性:术后平均等效球镜分别为(-0.11±0.44)D和(-0.07±0.44)D,在目标值±0.50D以内分别为83.1%和80.3%,±0.25D以内均为57.6%。"%稳定性:术后第1、第3和第6个月的平均等效球镜为-0.02966D和0.096591D,-0.09746D和0.003788D,-0.11441D和-0.07197D,变化均小于0.25D。上述4种指标均未见统计学差异。&"术后Q值分别为0.42±0.21和0.107±0.23,两者差异有显著性。结论6个月的随访结果显示,两组具有较高的安全性、有效性、可预测性和稳定性;Q值调整的个体化切削比标准切削更有助于维持角膜生理性的非球面性。其远期效果仍需更多病例、更全面的评价指标和更长时间的随访和研究。展开更多
基金National Scientific Research Target Project of China (2001-BA601B01-01-05) during the tenth Five-year Plan.
文摘Based on 310 horizontal-component digital seismograms recorded at 14 seismic stations in Shanxi Digital Seis-mograph Network, the inelastic attenuation coefficient in Shanxi region is studied. By the methods of Atkinson and Moya, the site response of each station and several source parameters are obtained and the inversion results from both methods are compared and analyzed. The frequency-dependent inelastic attenuation coefficient Q is estimated as Q( f )=323.2 f 0.506. The site responses of 14 seismic stations do not show significant amplification, which is consistent with their basement on rock. We also found the dependence of corner frequency on seismic moment, seismic moment on stress drop, source radius on stress drop.
基金The National Natural Science Foundation of China(90511001 and 30521002)an Action Plan for the Development of Western China of Chinese Academy of Science(KZCX2-XB2-01-04)a Knowledge Innovation Project of Chinese Academy of Sciences(KSCX2-SW-127).
文摘Aims Precipitation pulses and different land use practices(such as grazing)play important roles in regulating soil respiration and carbon balance of semiarid steppe ecosystems in Inner Mongolia.However,the interactive effects of grazing and rain event magnitude on soil respiration of steppe ecosystems are still unknown.We conducted a manipulative experiment with simulated precipitation pulses in Inner Mongolia steppe to study the possible responses of soil respiration to different precipitation pulse sizes and to examine how grazing may affect the responses of soil respiration to precipitation pulses.Methods Six water treatments with different precipitation pulse sizes(0,5,10,25,50 and 100 mm)were conducted in the ungrazed and grazed sites,respectively.Variation patterns of soil respiration of each treatment were determined continuously after the water addition treatments.Important Findings Rapid and substantial increases in soil respiration occurred 1 day after the water treatments in both sites,and the magnitude and duration of the increase in soil respiration depended on pulse size.Significantly positive relationships between the soil respiration and soil moisture in both sites suggested that soil moisture was the most important factor responsible for soil respiration rate during rain pulse events.The ungrazed site maintained significantly higher soil moisture for a longer time,which was the reason that the soil respiration in the ungrazed site was maintained relatively higher rate and longer period than that in the grazed site after a rain event.The significant exponential relationship between soil temperature and soil respiration was found only in the plots with the high water addition treatments(50 and 100 mm).Lower capacity of soil water holding and lower temperature sensitivity of soil respiration in the grazed site indicated that degraded steppe due to grazing might release less CO_(2) to the atmosphere through soil respiration under future precipitation and temperature scenarios.
文摘目的探讨Q值调整的个体化切削准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)治疗近视的安全性、有效性、可预测性和稳定性。方法应用美国雷赛Astramax三维角膜地形图仪、Astrapro个体化切削设计程序和Astrascan XL准分子激光系统,对33例(66眼)近视患者行Q值调整的个体化LASIK手术。30例(59眼)近视患者作为对照组行标准切削方式的LASIK手术。随访6个月,评价手术疗效。结果标准组和Q值组术后第6个月结果:"!安全性:两组均无一眼下降2行及以上,下降一行的各仅为2眼。"#有效性:术后裸眼视力分别为5.04±0.06和5.05±0.07,5.0以上分别为89.8%和90.9%,5.1以上为49.2%和50.0%。"$可预测性:术后平均等效球镜分别为(-0.11±0.44)D和(-0.07±0.44)D,在目标值±0.50D以内分别为83.1%和80.3%,±0.25D以内均为57.6%。"%稳定性:术后第1、第3和第6个月的平均等效球镜为-0.02966D和0.096591D,-0.09746D和0.003788D,-0.11441D和-0.07197D,变化均小于0.25D。上述4种指标均未见统计学差异。&"术后Q值分别为0.42±0.21和0.107±0.23,两者差异有显著性。结论6个月的随访结果显示,两组具有较高的安全性、有效性、可预测性和稳定性;Q值调整的个体化切削比标准切削更有助于维持角膜生理性的非球面性。其远期效果仍需更多病例、更全面的评价指标和更长时间的随访和研究。
