Celestial navigation system is an important autonomous navigation system widely used for deep space exploration missions, in which extended Kalman filter and the measurement of angle between celestial bodies are used ...Celestial navigation system is an important autonomous navigation system widely used for deep space exploration missions, in which extended Kalman filter and the measurement of angle between celestial bodies are used to estimate the position and velocity of explorer. In a conventional cartesian coordinate, this navigation system can not be used to achieve accurate determination of position for linearization errors of nonlinear spacecraft motion equation. A new autonomous celestial navigation method has been proposed for lunar satellite using classical orbital parameters. The error of linearizafion is reduced because orbit parameters change much more slowly than the position and velocity used in the cartesian coordinate. Simulations were made with both the cartesiane system and a system based on classical orbital parameters using extended Kalman filter under the same conditions for comparison. The results of comparison demonstrated high precision position determination of lunar satellite using this new method.展开更多
T cells are derived from progenitor thymocytes, of which only a minority receive the appropriate TCR signal, undergo positive selection and mature. Owing to the very short lifespan of thymocytes, the prerequisite for ...T cells are derived from progenitor thymocytes, of which only a minority receive the appropriate TCR signal, undergo positive selection and mature. Owing to the very short lifespan of thymocytes, the prerequisite for posi- tive selection is survival. TCR signal-induced Bcl-2 expression is believed to play a dominant role in the survival of positively selecting thymocytes, but how Bcl-2 is directly regulated is unknown. Here we report that the immediate early gene （IEG） c-Fos can stimulate the expression of Bcl-2, depending on a specific AP-l-binding site in the Bcl-2 promoter. In c-Fos transgenic （Fos-Tg） mice, c-Fos binds to this site and promotes the expression of Bcl-2. As a result, Fos-Tg thymocytes exhibited enhanced survival, and more mature single-positive （SP） thymocytes were generated, even on a unique TCR background. The TCR repertoire remained normal in Fos-Tg mice. Our results identified c-Fos as the mediator of the stimulatory effect of TCR signaling on Bcl-2 expression. Therefore, c-Fos, as an IEG, because of its early response ability, can quickly rescue the survival of short-lived thymocytes during positive selection. Our results provide novel insight into the mechanism regulating the survival of positively selecting thymocytes.展开更多
The driving force for China's industrial growth has shifted from the synergy of efficiency and factor input to the dominance of capital input alone.With the boundary of 2003,the contribution of capital to the grow...The driving force for China's industrial growth has shifted from the synergy of efficiency and factor input to the dominance of capital input alone.With the boundary of 2003,the contribution of capital to the growth of China's industrial economy increased from the annual average of 34.07%to 89.28%while the contribution of TFP dived from the annual average of 47.34%to-4.08%.Meanwhile,TFP growth rates dropped from the annual average of 4.6%to-0.05%and marginal capital output ratio went down from0.61 in 2002 to 0.28 in 2012.This indicates that the investment-driven pattern of China's industrial growth has been confronted with severe inefficiency.Further research suggests that the tendency of worsening industrial growth efficiency already became significant prior to the global financial crisis of 2008 and the eruption of the global financial crisis is not the fundamental reason for the worsening of efficiency and only exacerbated its tendency.The current government-led and investment-driven pattern of industrial growth is the root cause of such efficiency deterioration.Therefore,in order to achieve the transition towards innovation- and efficiency-driven growth pattern,the key is to make an appropriate distinction in the relationship between market and government,i.e.,the government must create a perfect institutional system where the market plays a decisive role and take proactive initiative to promote technology innovation and transfer on the basis of respecting market mechanism and the intent of market entities.展开更多
Background Postprocedural aortic regurgitations following transcatheter aortic valve implantation （TAVI） procedures remain an is- sue. Benefit of oversizing strategies to prevent them isn＇t well established. We com...Background Postprocedural aortic regurgitations following transcatheter aortic valve implantation （TAVI） procedures remain an is- sue. Benefit of oversizing strategies to prevent them isn＇t well established. We compared different level of oversizing in our cohort of con- secutive patients to address if severe oversizing compared to normal sizing had an impact on post-procedural outcomes. Methods From January 2010 to August 2013, consecutive patients were referred for TAVI with preoperative Multislice-CT （MSCT） and the procedures were achieved using Edwards Sapien~ or Corevalve devices~. Retrospectively, according to pre-procedural MSCT and the valve size, pa- tients were classified into three groups： normal, moderate and severe oversizing; depending on the ratio between the prosthesis area and the annulus area indexed and measured on MSCT. Main endpoint was mid-term mortality and secondary endpoints were the Valve Academic Research Consortium （VARC-2） endpoints. Results Two hundred and sixty eight patients had a MSCT and underwent TAVI procedure, with mainly Corevalve~. While all-cause and cardiovascular mortality rates were similar in all groups, post-procedural new pacemaker （PM） implantation rate was significantly higher in the severe oversizing group （P = 0.03）, while we observed more in-hospital congestive heart-failure （P = 0.02） in the normal sizing group. There was a trend toward more moderate to severe aortic regurgitation （AR） in the normal sizing group （P = 0.07）. Conclusions Despite a higher rate of PM implantation, oversizing based on this ratio reduces aortic leak with lower rates of post-procedural complications and a similar mid-term survival.展开更多
Two series monot ailed porphyrins, Cobalt-5- {4- [ω- （1-adamant aneamino） alkyloxy] phenyl }- 10,15,20-triphenyl porphyrinate （CoPCnA, n=4,5,6） and Nickel-5-{4-[ω-（1-adamantaneamino）alkyloxy]phenyl}-10,15.20- ...Two series monot ailed porphyrins, Cobalt-5- {4- [ω- （1-adamant aneamino） alkyloxy] phenyl }- 10,15,20-triphenyl porphyrinate （CoPCnA, n=4,5,6） and Nickel-5-{4-[ω-（1-adamantaneamino）alkyloxy]phenyl}-10,15.20- triphenyl porphyrinate （NiPCnA, n=4,5,6）, were synthesized, in which the porphyrin moiety was connected to l-adamantanamine via a flexible hydrocarbon chain. The fluorescence quenching between these donor substrates and mono-6-p-nitrobenzoyl-β-cyclodextrin （NBCD） was studied in detail. Distinct fluorescence quenching occured in these supramolecular systems. This quenching was attributed to the photoinduced electron transfer （PET） inside the supramolecular assembly between the porphyrin donors and cyclodextrin acceptors. Detailed Stern-Volmer constants were measured and they were partitioned into dynamic Stern- Volmer quenching constants and static binding constants. It was demonstrated that the PET interaction between the porphyrin subunits and NBCD is indeed effective.展开更多
In the context of Chinese learning English writing to learn and length approach is one of the highlighted concepts and practices. It entails sufficient comprehensible input and active interaction. It is found that the...In the context of Chinese learning English writing to learn and length approach is one of the highlighted concepts and practices. It entails sufficient comprehensible input and active interaction. It is found that the theme-based modules/units, if organized and performed meaningfully and closely related to the learners' life and experiences, will best integrate these three elements in the process of the second language learning, which is geared in some major aspects to the whole language philosophy. 'Writing to learn' is a product of reverse thinking. In a theme-based module/unit, a writing task of the same theme is put at its end with some requirements for language enhancement. It serves as an engine to learn other skills. In reality, it is not writing alone that functions in the SLA, but writing at the final stage that requires comprehended input and good qualitative interaction together to fuel SLA. An experiment of 20 weeks shows the positive results for the model.展开更多
The surface of nanocrystals plays a dominant role in many of their physical and chemical properties.However,controllability and tunability of nanocrystal surfaces remain unsolved.Herein,we report that the surface chem...The surface of nanocrystals plays a dominant role in many of their physical and chemical properties.However,controllability and tunability of nanocrystal surfaces remain unsolved.Herein,we report that the surface chemistry of nanocrystals,such as near-infrared Ag_(2)Se quantum dots(QDs),is sizedependent and composition-tunable.The Ag_(2)Se QDs tend to form a stable metal complex on the surface to minimize the surface energy,and therefore the surface chemistry can be varied with particle size.Meanwhile,changes in surface inorganic composition lead to reorganization of the surface ligands,and the surface chemistry also varies with composition.Therefore,the surface chemistry of Ag_(2)Se QDs,responsible for the photoluminescence(PL)quantum yield and photostability,can be tuned by changing their size or composition.Accordingly,we demonstrate that the PL intensity of the Ag_(2)Se QDs can be tuned reversely by adjusting the degree of surface Ag^(+) enrichment via light irradiation or the addition of AgNO_(3).This work provides insight into the control of QD surface for desired PL properties.展开更多
China＇s 2012 leadership change revealed signs of factional divide at the top level. The elitist/princeling faction has outnumbered the populist faction. Princelings have better and stronger ties with the military, wh...China＇s 2012 leadership change revealed signs of factional divide at the top level. The elitist/princeling faction has outnumbered the populist faction. Princelings have better and stronger ties with the military, which tends to have a more hawkish view regarding any potential Taiwan independence. In Taiwan, changing social experiences have created a new Taiwan Residents identity, which is dif- ferent from that of the Chinese. People in Taiwan are increasingly thinking of themselves as Taiwan Residents instead of Chinese. On the mainland, Chinese popular nationalism has been on the rise, as anti-Taiwan independence remains one of the most nationalistic issues. When the forces of new identity and nationalism meet each other, a diverging path regarding the future of Taiwan is being created. Moreover, China＇s economic and military power continues to rise, giving China more confidence. I argue that the overall effect is that China＇s new leadership will increasingly have the capability to act tougher against any potential Taiwan Residents independence. The potential need to act tougher with Taiwan may be beyond the desire and control of Chinese elites due to the rise of popular nationalism in China and the leadership＇s need to maintain internal legitimacy and survival.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No. 60174031)China National Space Administration
文摘Celestial navigation system is an important autonomous navigation system widely used for deep space exploration missions, in which extended Kalman filter and the measurement of angle between celestial bodies are used to estimate the position and velocity of explorer. In a conventional cartesian coordinate, this navigation system can not be used to achieve accurate determination of position for linearization errors of nonlinear spacecraft motion equation. A new autonomous celestial navigation method has been proposed for lunar satellite using classical orbital parameters. The error of linearizafion is reduced because orbit parameters change much more slowly than the position and velocity used in the cartesian coordinate. Simulations were made with both the cartesiane system and a system based on classical orbital parameters using extended Kalman filter under the same conditions for comparison. The results of comparison demonstrated high precision position determination of lunar satellite using this new method.
文摘T cells are derived from progenitor thymocytes, of which only a minority receive the appropriate TCR signal, undergo positive selection and mature. Owing to the very short lifespan of thymocytes, the prerequisite for posi- tive selection is survival. TCR signal-induced Bcl-2 expression is believed to play a dominant role in the survival of positively selecting thymocytes, but how Bcl-2 is directly regulated is unknown. Here we report that the immediate early gene （IEG） c-Fos can stimulate the expression of Bcl-2, depending on a specific AP-l-binding site in the Bcl-2 promoter. In c-Fos transgenic （Fos-Tg） mice, c-Fos binds to this site and promotes the expression of Bcl-2. As a result, Fos-Tg thymocytes exhibited enhanced survival, and more mature single-positive （SP） thymocytes were generated, even on a unique TCR background. The TCR repertoire remained normal in Fos-Tg mice. Our results identified c-Fos as the mediator of the stimulatory effect of TCR signaling on Bcl-2 expression. Therefore, c-Fos, as an IEG, because of its early response ability, can quickly rescue the survival of short-lived thymocytes during positive selection. Our results provide novel insight into the mechanism regulating the survival of positively selecting thymocytes.
文摘The driving force for China's industrial growth has shifted from the synergy of efficiency and factor input to the dominance of capital input alone.With the boundary of 2003,the contribution of capital to the growth of China's industrial economy increased from the annual average of 34.07%to 89.28%while the contribution of TFP dived from the annual average of 47.34%to-4.08%.Meanwhile,TFP growth rates dropped from the annual average of 4.6%to-0.05%and marginal capital output ratio went down from0.61 in 2002 to 0.28 in 2012.This indicates that the investment-driven pattern of China's industrial growth has been confronted with severe inefficiency.Further research suggests that the tendency of worsening industrial growth efficiency already became significant prior to the global financial crisis of 2008 and the eruption of the global financial crisis is not the fundamental reason for the worsening of efficiency and only exacerbated its tendency.The current government-led and investment-driven pattern of industrial growth is the root cause of such efficiency deterioration.Therefore,in order to achieve the transition towards innovation- and efficiency-driven growth pattern,the key is to make an appropriate distinction in the relationship between market and government,i.e.,the government must create a perfect institutional system where the market plays a decisive role and take proactive initiative to promote technology innovation and transfer on the basis of respecting market mechanism and the intent of market entities.
文摘Background Postprocedural aortic regurgitations following transcatheter aortic valve implantation （TAVI） procedures remain an is- sue. Benefit of oversizing strategies to prevent them isn＇t well established. We compared different level of oversizing in our cohort of con- secutive patients to address if severe oversizing compared to normal sizing had an impact on post-procedural outcomes. Methods From January 2010 to August 2013, consecutive patients were referred for TAVI with preoperative Multislice-CT （MSCT） and the procedures were achieved using Edwards Sapien~ or Corevalve devices~. Retrospectively, according to pre-procedural MSCT and the valve size, pa- tients were classified into three groups： normal, moderate and severe oversizing; depending on the ratio between the prosthesis area and the annulus area indexed and measured on MSCT. Main endpoint was mid-term mortality and secondary endpoints were the Valve Academic Research Consortium （VARC-2） endpoints. Results Two hundred and sixty eight patients had a MSCT and underwent TAVI procedure, with mainly Corevalve~. While all-cause and cardiovascular mortality rates were similar in all groups, post-procedural new pacemaker （PM） implantation rate was significantly higher in the severe oversizing group （P = 0.03）, while we observed more in-hospital congestive heart-failure （P = 0.02） in the normal sizing group. There was a trend toward more moderate to severe aortic regurgitation （AR） in the normal sizing group （P = 0.07）. Conclusions Despite a higher rate of PM implantation, oversizing based on this ratio reduces aortic leak with lower rates of post-procedural complications and a similar mid-term survival.
基金V. ACKN0WLEDGMENT This work was supported Science Foundation of China by the National Natural （No.20472079）.
文摘Two series monot ailed porphyrins, Cobalt-5- {4- [ω- （1-adamant aneamino） alkyloxy] phenyl }- 10,15,20-triphenyl porphyrinate （CoPCnA, n=4,5,6） and Nickel-5-{4-[ω-（1-adamantaneamino）alkyloxy]phenyl}-10,15.20- triphenyl porphyrinate （NiPCnA, n=4,5,6）, were synthesized, in which the porphyrin moiety was connected to l-adamantanamine via a flexible hydrocarbon chain. The fluorescence quenching between these donor substrates and mono-6-p-nitrobenzoyl-β-cyclodextrin （NBCD） was studied in detail. Distinct fluorescence quenching occured in these supramolecular systems. This quenching was attributed to the photoinduced electron transfer （PET） inside the supramolecular assembly between the porphyrin donors and cyclodextrin acceptors. Detailed Stern-Volmer constants were measured and they were partitioned into dynamic Stern- Volmer quenching constants and static binding constants. It was demonstrated that the PET interaction between the porphyrin subunits and NBCD is indeed effective.
基金This paper is in a project sponsored by The Special Fund Construction of Guangdong Higher Education It was alsoselected to beincluded in the presentations at the 4th Asia TEFL Conferencein Fukuoka,Japan
文摘In the context of Chinese learning English writing to learn and length approach is one of the highlighted concepts and practices. It entails sufficient comprehensible input and active interaction. It is found that the theme-based modules/units, if organized and performed meaningfully and closely related to the learners' life and experiences, will best integrate these three elements in the process of the second language learning, which is geared in some major aspects to the whole language philosophy. 'Writing to learn' is a product of reverse thinking. In a theme-based module/unit, a writing task of the same theme is put at its end with some requirements for language enhancement. It serves as an engine to learn other skills. In reality, it is not writing alone that functions in the SLA, but writing at the final stage that requires comprehended input and good qualitative interaction together to fuel SLA. An experiment of 20 weeks shows the positive results for the model.
基金supported by the National Natural Science Foundation of China(91859123)the National Key R&D Program of China(2019YFA0210103)。
文摘The surface of nanocrystals plays a dominant role in many of their physical and chemical properties.However,controllability and tunability of nanocrystal surfaces remain unsolved.Herein,we report that the surface chemistry of nanocrystals,such as near-infrared Ag_(2)Se quantum dots(QDs),is sizedependent and composition-tunable.The Ag_(2)Se QDs tend to form a stable metal complex on the surface to minimize the surface energy,and therefore the surface chemistry can be varied with particle size.Meanwhile,changes in surface inorganic composition lead to reorganization of the surface ligands,and the surface chemistry also varies with composition.Therefore,the surface chemistry of Ag_(2)Se QDs,responsible for the photoluminescence(PL)quantum yield and photostability,can be tuned by changing their size or composition.Accordingly,we demonstrate that the PL intensity of the Ag_(2)Se QDs can be tuned reversely by adjusting the degree of surface Ag^(+) enrichment via light irradiation or the addition of AgNO_(3).This work provides insight into the control of QD surface for desired PL properties.
文摘China＇s 2012 leadership change revealed signs of factional divide at the top level. The elitist/princeling faction has outnumbered the populist faction. Princelings have better and stronger ties with the military, which tends to have a more hawkish view regarding any potential Taiwan independence. In Taiwan, changing social experiences have created a new Taiwan Residents identity, which is dif- ferent from that of the Chinese. People in Taiwan are increasingly thinking of themselves as Taiwan Residents instead of Chinese. On the mainland, Chinese popular nationalism has been on the rise, as anti-Taiwan independence remains one of the most nationalistic issues. When the forces of new identity and nationalism meet each other, a diverging path regarding the future of Taiwan is being created. Moreover, China＇s economic and military power continues to rise, giving China more confidence. I argue that the overall effect is that China＇s new leadership will increasingly have the capability to act tougher against any potential Taiwan Residents independence. The potential need to act tougher with Taiwan may be beyond the desire and control of Chinese elites due to the rise of popular nationalism in China and the leadership＇s need to maintain internal legitimacy and survival.
