Vegetation restoration has been proposed as an effective method for increasing both plant biomass and soil carbon(C) stocks. In this study, 204 publications(733 observations) were analyzed, focusing on the effects of ...Vegetation restoration has been proposed as an effective method for increasing both plant biomass and soil carbon(C) stocks. In this study, 204 publications(733 observations) were analyzed, focusing on the effects of vegetation restoration on soil organic carbon(SOC) in China. The results showed that SOC was increased by 45.33%, 24.43%, 30.29% and 27.98% at soil depths of 0–20 cm, 20–40 cm, 40–60 cm and > 60 cm after vegetation restoration, respectively. Restoration from both cropland and non-cropland increased the SOC content. The conversion of non-cropland was more efficient in SOC accumulation than the conversion of cropland did, especially in > 40 cm layers. In addition, the conversion to planted forest led to greater SOC accumulation than that to other land use did. Conversion period and initial SOC content extended more influence on soil C accumulation as the main factors after vegetation restoration than temperature and precipitation did. The SOC content significantly increased with restoration period after long-term vegetation restoration(> 40 yr), indicating a large potential for further accumulation of carbon in the soil, which could mitigate climate change in the near future.展开更多
A service life model of NAND flash and threshold voltage shift process is proposed to calculate the service life and endurance.The relationships among achievable program/erase(P/E) cycles,recovery time,bad block rate ...A service life model of NAND flash and threshold voltage shift process is proposed to calculate the service life and endurance.The relationships among achievable program/erase(P/E) cycles,recovery time,bad block rate and storage time are analyzed.The achievable endurance and service life of a NAND flash are evaluated based on a flash cell degradation and recovery model by varying recovery time,badblock rate,and storage time.It is proposed to improve the service lifetime of solid state disk by both relaxing the bad block rate limitation and retention time while extending the recovery time.The results indicate that endurance can be improved by 17 times if the storage time guarantee is reduced from 10 a to 1 a with 105 s recovery time inserted between cycles.展开更多
Optical Time Division Multiplexing （OTDM） is known to be capable of transmitting single channel high bit rate data stream with low speed electro-optical components. A cost-effective, compact and stable short time wi...Optical Time Division Multiplexing （OTDM） is known to be capable of transmitting single channel high bit rate data stream with low speed electro-optical components. A cost-effective, compact and stable short time window with low insert loss, low phase noise, low timing-jitter and high speed performance is essential for ultra-high speed OTDM systems using phase and amplitude modulation formats. In this paper, we review three promising methods to obtain 40 GHz short time window including Electro-Absorption Modulator （EAM）, Dual-Parallel Mach-Zehnder Modulator （DPMZM） and Fiber Loop-Polarization Modulator （FL-PolM）. Sub-picosecond short pulse source generation, optical time division denlaltiplexing and clock recovery are realized respectively by using the short time window based on the three methods. By using DPMZM based pulse source and EAM based Clock Recovery （CR） and dermltiplexer, error free transmission of 640 Goit/s （160 Gbaud/s Pol-Mux DQPSK） single channel signal over 400 km single mode fiber is proven to be experimentally successful.展开更多
Objective: The aim of this study was to explore clinical value of thoracic small incision in radical operation for lung and esophageal cancer in assuring same treatment effects with conventional incision. Methods: Col...Objective: The aim of this study was to explore clinical value of thoracic small incision in radical operation for lung and esophageal cancer in assuring same treatment effects with conventional incision. Methods: Collected data of patients was given radical operation for lung and esophageal cancer in our department from January 1, 2006 to January 1, 2007, and performed retrospective analysis, among them, small incision group (improved group) was 143 cases, and conventional group was 167 cases including 6 cases which was changed from small incision to conventional incision in operation. Compared operation time, incision length, intraoperative blood loss, postoperative drainage flow, number of lymph node dissected, recovery time of postoperative upper limb function, postoperative pain, postoperative complications etc. between both groups. Results: Compared with conventional group, intraoperative blood loss, postoperative drainage flow, postoperative pain, recovery time of postoperative upper limb function in improved group was improved significantly, and there was no obvious difference in operation time and number of lymph node dissected between both groups. Conclusion: Small incision in radical operation for lung and esophageal cancer is small trauma, and quick recovery after operation, treatment effects of it is basically similar to that of conventional operation method, however, its application is limited in few cases.展开更多
基金Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05060104)
文摘Vegetation restoration has been proposed as an effective method for increasing both plant biomass and soil carbon(C) stocks. In this study, 204 publications(733 observations) were analyzed, focusing on the effects of vegetation restoration on soil organic carbon(SOC) in China. The results showed that SOC was increased by 45.33%, 24.43%, 30.29% and 27.98% at soil depths of 0–20 cm, 20–40 cm, 40–60 cm and > 60 cm after vegetation restoration, respectively. Restoration from both cropland and non-cropland increased the SOC content. The conversion of non-cropland was more efficient in SOC accumulation than the conversion of cropland did, especially in > 40 cm layers. In addition, the conversion to planted forest led to greater SOC accumulation than that to other land use did. Conversion period and initial SOC content extended more influence on soil C accumulation as the main factors after vegetation restoration than temperature and precipitation did. The SOC content significantly increased with restoration period after long-term vegetation restoration(> 40 yr), indicating a large potential for further accumulation of carbon in the soil, which could mitigate climate change in the near future.
基金Project(61171017)supported by the National Natural Science Foundation of China
文摘A service life model of NAND flash and threshold voltage shift process is proposed to calculate the service life and endurance.The relationships among achievable program/erase(P/E) cycles,recovery time,bad block rate and storage time are analyzed.The achievable endurance and service life of a NAND flash are evaluated based on a flash cell degradation and recovery model by varying recovery time,badblock rate,and storage time.It is proposed to improve the service lifetime of solid state disk by both relaxing the bad block rate limitation and retention time while extending the recovery time.The results indicate that endurance can be improved by 17 times if the storage time guarantee is reduced from 10 a to 1 a with 105 s recovery time inserted between cycles.
基金Acknowledgements This paper was partially supported by the Hi-Tech Research andDevelopment Program of China under Grant No. 2012AA011303 the National Natural Science Foundation of China under Crants No. 61001121, No. 60932004, No. 61006041+1 种基金 the National Key Basic Research Program of China under Grant No. 2011CB301702 the Fundamental Research Funds for the Central Universities.
文摘Optical Time Division Multiplexing （OTDM） is known to be capable of transmitting single channel high bit rate data stream with low speed electro-optical components. A cost-effective, compact and stable short time window with low insert loss, low phase noise, low timing-jitter and high speed performance is essential for ultra-high speed OTDM systems using phase and amplitude modulation formats. In this paper, we review three promising methods to obtain 40 GHz short time window including Electro-Absorption Modulator （EAM）, Dual-Parallel Mach-Zehnder Modulator （DPMZM） and Fiber Loop-Polarization Modulator （FL-PolM）. Sub-picosecond short pulse source generation, optical time division denlaltiplexing and clock recovery are realized respectively by using the short time window based on the three methods. By using DPMZM based pulse source and EAM based Clock Recovery （CR） and dermltiplexer, error free transmission of 640 Goit/s （160 Gbaud/s Pol-Mux DQPSK） single channel signal over 400 km single mode fiber is proven to be experimentally successful.
文摘Objective: The aim of this study was to explore clinical value of thoracic small incision in radical operation for lung and esophageal cancer in assuring same treatment effects with conventional incision. Methods: Collected data of patients was given radical operation for lung and esophageal cancer in our department from January 1, 2006 to January 1, 2007, and performed retrospective analysis, among them, small incision group (improved group) was 143 cases, and conventional group was 167 cases including 6 cases which was changed from small incision to conventional incision in operation. Compared operation time, incision length, intraoperative blood loss, postoperative drainage flow, number of lymph node dissected, recovery time of postoperative upper limb function, postoperative pain, postoperative complications etc. between both groups. Results: Compared with conventional group, intraoperative blood loss, postoperative drainage flow, postoperative pain, recovery time of postoperative upper limb function in improved group was improved significantly, and there was no obvious difference in operation time and number of lymph node dissected between both groups. Conclusion: Small incision in radical operation for lung and esophageal cancer is small trauma, and quick recovery after operation, treatment effects of it is basically similar to that of conventional operation method, however, its application is limited in few cases.
