目的 :研究联合腹腔干的胰体尾切除(distal pancreatectomy with en bloc celiac axis resection, DP-CAR)对扩大根治局部进展期胰体尾癌的近期临床疗效,并探讨血管变异对DP-CAR术后并发症发生的影响。方法:回顾性研究43例行DP-CAR且术...目的 :研究联合腹腔干的胰体尾切除(distal pancreatectomy with en bloc celiac axis resection, DP-CAR)对扩大根治局部进展期胰体尾癌的近期临床疗效,并探讨血管变异对DP-CAR术后并发症发生的影响。方法:回顾性研究43例行DP-CAR且术后病理结果均为胰腺导管腺癌的病例,分析R0切除率和围术期手术并发症发生率、死亡率等,比较有无血管变异对术后并发症发生的影响。结果:本研究DP-CAR的R0切除率达81.4%,围术期死亡率为7.0%,并发症发生率为46.5%。腹腔血管变异8例。血管变异组与无血管变异组术后并发症发生率为3/8(37.5%)比17/35(48.6%),P=0.535,死亡率为1/8(12.5%)比2/35(5.7%),P=0.224,组间差异均无统计学意义。结论:DP-CAR具有一定的优越性,安全可行。血管变异对DP-CAR术后并发症发生无显著影响。展开更多
Reeves＇s Pheasant （Syrmaticus reevesii） is a threatened pheasant species endemic to China. The habitat use of territorial male birds was surveyed by the help of live decoys in a core area of Dongzhai NationaI Natur...Reeves＇s Pheasant （Syrmaticus reevesii） is a threatened pheasant species endemic to China. The habitat use of territorial male birds was surveyed by the help of live decoys in a core area of Dongzhai NationaI Nature Reserve. The breeding habitat selection of this pheasant was examined at two scales （115 m and 250 m scale, i.e. 4.15 hm^2 and 19.63 hm^2, respectively）, including the characteristics at distance scale. Investigation was based on line transect, RS and GIS in Dongzhai National Natural Reserve from 2001 to 2003. Moreover, a range of habitat variables were compared between used and control points at each scale, and stepwise logistic regression was applied to select the key scale and the key habitat factors in relation to breeding habitat selection of this bird. Our results stated that the territorial males at Baiyun occurred mostly in mixed forests, followed by fir forests, pine forests, shrubs, and broadleaf forests. The area of conifer forests was the key factor influencing habitat selection of this bird in breeding period at the scales of 115 m and 250 m, and the proximity of farmland was important for habitat selection in breeding seasons. Furthermore, Reeves＇s Pheasants attached great importance to the scale of 115 m. When considering a range of habitat variables at all scales within a multivariate regression, the leading factors having effect on habitat selection in the breeding period were areas of conifer forests at 115 m scale and the distance to farmland. In addition, these above results suggested that strengthening the management of suitable habitat, and optimizing the habitat configuration are important in promoting conservation of this bird. However, it also highlighted the importance of initiating future researches on the conifer forests and their impact on the population of Reeves＇s Pheasants, which would be beneficial to promote the habitat conservation of this pheasant more effectively.展开更多
To better understand the characteristics of air quality and the relationship between the chemical composition evolution and source variation,an intensive atmospheric campaign was conducted in Tianjin,a megacity of the...To better understand the characteristics of air quality and the relationship between the chemical composition evolution and source variation,an intensive atmospheric campaign was conducted in Tianjin,a megacity of the North China Plain,from 10 February to 6 March 2015.There were 20 days exceeding the threshold value of secondary Chinese Ambient Air Quality Standards for PM2.5(75 μg m-3,daily average over 24 h)during the study period.Five air pollution episodes were selected for investigation.During the pre-holiday pollution episode,NH^+_4,NO^-_3,and SO^(2-)_4 were more abundant,indicating that air pollution was caused by motor vehicle exhaust emissions and coal consumption under unfavorable meteorological conditions.During Chinese Lunar New Year's Eve,widespread use of fireworks resulted in extremely high aerosol concentrations.Firework displays caused increases in K+ and also enrichment of SO^(2-)_4 relative to NO^-_3.The holiday pollution episode was caused by regional transport,characterized by abundant SO^(2-)_4 and NH^+_4.In addition,the aging processes of the particles from fireworks discharge played an important role in the formation of NO-3and SO^(2-)_4.The Lantern Festival episode was characterized by a transition from the enrichment of K+ to secondary inorganic ions(NO^-_3,SO^(2-)_4,and NH^+_4).The results of this study are useful for a detailed understanding of the variation in atmospheric compositions and sources caused by anthropogenic activity,and highlight the importance of controlling intensive fireworks discharge.展开更多
Pluripotent stem cells derived from neonatal or adult testes are a useful tool to examine the mechanisms of pluripotency and a resource for cell-based therapies. However, therapies usingthese cells will only benefit m...Pluripotent stem cells derived from neonatal or adult testes are a useful tool to examine the mechanisms of pluripotency and a resource for cell-based therapies. However, therapies usingthese cells will only benefit males but not females. Recently, female germline stem cells （FGSCs） were discovered in ovaries. Whether FGSCs can be converted into pluripotent stem cells, similar to spermatogonial stem cells, is unknown. Here, we demonstrate that female embryonic stem-like cells （fESLCs） can be generated within 1 month from the stably proliferating FGSCs cultured in embryonic stem cell （ESC） medium, fESLCs exhibit properties similar to those of ESCs in terms of marker expression and differentiation potential. Thus, our findings suggest that generation of patient-specific fESLCs is feasible and provides a foundation for personalized regenerative applications.展开更多
In this study,we aim at developing a model for option pricing to reduce the risks associated with Ethiopian coffee price fluctuations.We used daily closed Washed Sidama class A Grade3(WSDA3)coffee price recorded in th...In this study,we aim at developing a model for option pricing to reduce the risks associated with Ethiopian coffee price fluctuations.We used daily closed Washed Sidama class A Grade3(WSDA3)coffee price recorded in the period 31 May 2011 to 30 March 2018 obtained from Ethiopia commodity exchange(ECX)market to analyse the price fluctuation.The nature of log-returns of the price is asymmetric(negatively skewed)and exhibits high kurtosis.We used jump diffusion models for modeling and option pricing the coffee price.The method of maximum likelihood is applied to estimate the parameters of the models.We used the root mean square error(RMSE)to test the validation of the models.The values of RMSE for Merton’s and double exponential jump diffusion models are 0.1093 and 0.0783,respectively.These results indicate that the models fit the data very well.We used analytical and Monte Carlo technique to find the call option pricing of WSDA3 price.Based on the empirical results,we concluded that double exponential jump diffusion model is more efficient than Merton’s model for modeling and option pricing of this coffee price.展开更多
文摘目的 :研究联合腹腔干的胰体尾切除(distal pancreatectomy with en bloc celiac axis resection, DP-CAR)对扩大根治局部进展期胰体尾癌的近期临床疗效,并探讨血管变异对DP-CAR术后并发症发生的影响。方法:回顾性研究43例行DP-CAR且术后病理结果均为胰腺导管腺癌的病例,分析R0切除率和围术期手术并发症发生率、死亡率等,比较有无血管变异对术后并发症发生的影响。结果:本研究DP-CAR的R0切除率达81.4%,围术期死亡率为7.0%,并发症发生率为46.5%。腹腔血管变异8例。血管变异组与无血管变异组术后并发症发生率为3/8(37.5%)比17/35(48.6%),P=0.535,死亡率为1/8(12.5%)比2/35(5.7%),P=0.224,组间差异均无统计学意义。结论:DP-CAR具有一定的优越性,安全可行。血管变异对DP-CAR术后并发症发生无显著影响。
基金supported by the National Sciences Foundation of China (30800103)the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China (2008BADB0B01)~~
文摘Reeves＇s Pheasant （Syrmaticus reevesii） is a threatened pheasant species endemic to China. The habitat use of territorial male birds was surveyed by the help of live decoys in a core area of Dongzhai NationaI Nature Reserve. The breeding habitat selection of this pheasant was examined at two scales （115 m and 250 m scale, i.e. 4.15 hm^2 and 19.63 hm^2, respectively）, including the characteristics at distance scale. Investigation was based on line transect, RS and GIS in Dongzhai National Natural Reserve from 2001 to 2003. Moreover, a range of habitat variables were compared between used and control points at each scale, and stepwise logistic regression was applied to select the key scale and the key habitat factors in relation to breeding habitat selection of this bird. Our results stated that the territorial males at Baiyun occurred mostly in mixed forests, followed by fir forests, pine forests, shrubs, and broadleaf forests. The area of conifer forests was the key factor influencing habitat selection of this bird in breeding period at the scales of 115 m and 250 m, and the proximity of farmland was important for habitat selection in breeding seasons. Furthermore, Reeves＇s Pheasants attached great importance to the scale of 115 m. When considering a range of habitat variables at all scales within a multivariate regression, the leading factors having effect on habitat selection in the breeding period were areas of conifer forests at 115 m scale and the distance to farmland. In addition, these above results suggested that strengthening the management of suitable habitat, and optimizing the habitat configuration are important in promoting conservation of this bird. However, it also highlighted the importance of initiating future researches on the conifer forests and their impact on the population of Reeves＇s Pheasants, which would be beneficial to promote the habitat conservation of this pheasant more effectively.
基金supported by the Beijing Natural Science Foundation[grant number 8142034]Strategic Priority Research Program(B)of the Chinese Academy of Sciences[grant numbers XDB0502050 and XDB05030203]
文摘To better understand the characteristics of air quality and the relationship between the chemical composition evolution and source variation,an intensive atmospheric campaign was conducted in Tianjin,a megacity of the North China Plain,from 10 February to 6 March 2015.There were 20 days exceeding the threshold value of secondary Chinese Ambient Air Quality Standards for PM2.5(75 μg m-3,daily average over 24 h)during the study period.Five air pollution episodes were selected for investigation.During the pre-holiday pollution episode,NH^+_4,NO^-_3,and SO^(2-)_4 were more abundant,indicating that air pollution was caused by motor vehicle exhaust emissions and coal consumption under unfavorable meteorological conditions.During Chinese Lunar New Year's Eve,widespread use of fireworks resulted in extremely high aerosol concentrations.Firework displays caused increases in K+ and also enrichment of SO^(2-)_4 relative to NO^-_3.The holiday pollution episode was caused by regional transport,characterized by abundant SO^(2-)_4 and NH^+_4.In addition,the aging processes of the particles from fireworks discharge played an important role in the formation of NO-3and SO^(2-)_4.The Lantern Festival episode was characterized by a transition from the enrichment of K+ to secondary inorganic ions(NO^-_3,SO^(2-)_4,and NH^+_4).The results of this study are useful for a detailed understanding of the variation in atmospheric compositions and sources caused by anthropogenic activity,and highlight the importance of controlling intensive fireworks discharge.
基金Funding This work was supported by National Basic Research Program of China （2013CB967401 and 2010CB945001）, and the National Nature Science Foundation of China （81370675 and 81121001）.
文摘Pluripotent stem cells derived from neonatal or adult testes are a useful tool to examine the mechanisms of pluripotency and a resource for cell-based therapies. However, therapies usingthese cells will only benefit males but not females. Recently, female germline stem cells （FGSCs） were discovered in ovaries. Whether FGSCs can be converted into pluripotent stem cells, similar to spermatogonial stem cells, is unknown. Here, we demonstrate that female embryonic stem-like cells （fESLCs） can be generated within 1 month from the stably proliferating FGSCs cultured in embryonic stem cell （ESC） medium, fESLCs exhibit properties similar to those of ESCs in terms of marker expression and differentiation potential. Thus, our findings suggest that generation of patient-specific fESLCs is feasible and provides a foundation for personalized regenerative applications.
文摘In this study,we aim at developing a model for option pricing to reduce the risks associated with Ethiopian coffee price fluctuations.We used daily closed Washed Sidama class A Grade3(WSDA3)coffee price recorded in the period 31 May 2011 to 30 March 2018 obtained from Ethiopia commodity exchange(ECX)market to analyse the price fluctuation.The nature of log-returns of the price is asymmetric(negatively skewed)and exhibits high kurtosis.We used jump diffusion models for modeling and option pricing the coffee price.The method of maximum likelihood is applied to estimate the parameters of the models.We used the root mean square error(RMSE)to test the validation of the models.The values of RMSE for Merton’s and double exponential jump diffusion models are 0.1093 and 0.0783,respectively.These results indicate that the models fit the data very well.We used analytical and Monte Carlo technique to find the call option pricing of WSDA3 price.Based on the empirical results,we concluded that double exponential jump diffusion model is more efficient than Merton’s model for modeling and option pricing of this coffee price.
