The Weyl double copy builds the relation between gauge theory and gravity theory, in particular the correspondence between gauge solutions and gravity solutions. In this paper, we obtain the slowly rotating charge sol...The Weyl double copy builds the relation between gauge theory and gravity theory, in particular the correspondence between gauge solutions and gravity solutions. In this paper, we obtain the slowly rotating charge solutions from the Weyl double copy for the Kerr black hole with small Chern-Simons correction. Based on the Weyl double copy relation, for the Petrov type D solution in Chern-Simons modified gravity, we find the additional correction to the electromagnetic field strength tensor of the rotating charge. For the Petrov type I solution, we find that the additional electromagnetic field strength tensors have external sources, while the total sources vanish at the leading order.展开更多
A high-performance vibration isolation platform （VIP） has been developed for a cluster of control moment gyroscopes （CMGs）. CMGs have long been used for satellite attitude control. In this paper, the influence of ...A high-performance vibration isolation platform （VIP） has been developed for a cluster of control moment gyroscopes （CMGs）. CMGs have long been used for satellite attitude control. In this paper, the influence of flexible solar arrays on a passive multi-strut VIP of CMGs for a satellite is analyzed. The reasonable parameters design of flexi- ble solar arrays is discussed. Firstly, the dynamic model of the integrated satellite with flexible solar arrays, the VIP and CMGs is conducted by Newton-Euler method. Then based on reasonable assumptions, the transmissibility matrix of the VIP is derived. Secondly, the influences of the flexible solar arrays on both the performance of the VIP and the stability of closed-loop control systems are analyzed in detail. The parameter design limitation of these solar arrays is discussed. At last, by selecting reasonable parameters for both the VIP and flexible solar arrays, the attitude stabilization performance with vibration isolation system is predicted via simulation.展开更多
In remote sensing or laser communication space missions, spacecraft need fast maneuver and fast stabilization in order to accomplish agile imaging and attitude tracking tasks. However, fast attitude maneuvers can easi...In remote sensing or laser communication space missions, spacecraft need fast maneuver and fast stabilization in order to accomplish agile imaging and attitude tracking tasks. However, fast attitude maneuvers can easily cause elastic deformations and vibrations in flexible appendages of the spacecraft. This paper focuses on this problem and deals with the combined control of fast attitude maneuver and sta- bilization for large complex spacecraft. The mathematical model of complex spacecraft with flexible appendages and momentum bias actuators on board is presented. Based on the plant model and combined with the feedback controller, modal parameters of the closed-loop system are calculated, and a multiple mode input shaper utilizing the modal information is designed to suppress vibrations. Aiming at reducing vibrations excited by attitude maneuver, a quintic polynomial form rotation path planning is proposed with constraints on the actuators and the angular velocity taken into account. Attitude maneuver simulation results of the control systems with input shaper or path planning in loop are sepa- rately analyzed, and based on the analysis, a combined control strategy is presented with both path planning and input shaper in loop. Simulation results show that the combined control strategy satisfies the complex spacecraft＇s require- ment of fast maneuver and stabilization with the actuators＇ torque limitation satisfied at the same time.展开更多
BACKGROUND Patients with atrial fibrillation(AF)and prior stroke history have a high risk of cardiovascular events despite anticoagulation therapy.It is unclear whether catheter ablation(CA)has further benefits in the...BACKGROUND Patients with atrial fibrillation(AF)and prior stroke history have a high risk of cardiovascular events despite anticoagulation therapy.It is unclear whether catheter ablation(CA)has further benefits in these patients.METHODS AF patients with a previous history of stroke or systemic embolism(SE)from the prospective Chinese Atrial Fibrillation Registry study between August 2011 and December 2020 were included in the analysis.Patients were matched in a 1:1 ratio to CA or medical treatment(MT)based on propensity score.The primary outcome was a composite of all-cause death or ischemic stroke(IS)/SE.RESULTS During a total of 4.1±2.3 years of follow-up,the primary outcome occurred in 111 patients in the CA group(3.3 per 100 person-years)and in 229 patients in the MT group(5.7 per 100 person-years).The CA group had a lower risk of the primary outcome compared to the MT group[hazard ratio(HR)=0.59,95%CI:0.47–0.74,P<0.001].There was a significant decreasing risk of all-cause mortality(HR=0.43,95%CI:0.31–0.61,P<0.001),IS/SE(HR=0.73,95%CI:0.54–0.97,P=0.033),cardiovascular mortality(HR=0.32,95%CI:0.19–0.54,P<0.001)and AF recurrence(HR=0.33,95%CI:0.30–0.37,P<0.001)in the CA group compared to that in the MT group.Sensitivity analysis generated consistent results when adjusting for time-dependent usage of anticoagulants.CONCLUSIONS In AF patients with a prior stroke history,CA was associated with a lower combined risk of all-cause death or IS/SE.Further clinical trials are warranted to confirm the benefits of CA in these patients.展开更多
Stability against oxygen is an important factor affecting the performance of organic semiconductor devices.Improving photooxidation stability can prolong the service life of the device and maintain the mechanical and ...Stability against oxygen is an important factor affecting the performance of organic semiconductor devices.Improving photooxidation stability can prolong the service life of the device and maintain the mechanical and photoelectric properties of the device.Generally,various encapsulation methods from molecular structure to macroscopic device level are used to improve photooxidation stability.Here,we adopted a crystallization strategy to allow 14H-spiro[dibenzo[c,h]acridine-7,9′-fluorene](SFDBA)to pack tightly to resist fluorescence decay caused by oxidation.In this case,the inert group of SFDBA acts as a“steric armor”,protecting the photosensitive group from being attacked by oxygen.Therefore,compared with the fluorescence quenching of SFDBA powder under 2 h of sunlight,SFDBA crystal can maintain its fluorescence emission for more than 8 h under the same conditions.Furthermore,the photoluminescence quantum yields(PLQYs)of the crystalline film is 327%higher than that of the amorphous film.It shows that the crystallization strategy is an effective method to resist oxidation.展开更多
To the Editor:Atrial fibrillation(AF)is one of the leading risk factors for stroke and is associated with a fivefold increase in the incidence of stroke.For years,warfarin has been prescribed to lower the thrombotic r...To the Editor:Atrial fibrillation(AF)is one of the leading risk factors for stroke and is associated with a fivefold increase in the incidence of stroke.For years,warfarin has been prescribed to lower the thrombotic risk in patients with AF.However,because of the finicky nature of warfarin(ie,unpredictable pharmacokinetics,frequent international normalized ratio testing,complex food-drug interactions,etc.),it has been incrementally replaced by multiple direct oral anticoagulants(DOACs).Dabigatran,a potent,competitive,and reversible DOAC that directly targets thrombin,was approved by the US Food and Drug Administration in 2010 as an alternative antithrombotic option for nonvalvular AF.While the randomized evaluation of long-term anticoagulation therapy(RE-LY)trial(a noninferiority trial comparing warfarin with dabigatran in patients with AF)showed that dabigatran is as successful as warfarin for preventing stroke or systemic embolism,its adverse effects also need attention.[1]Accumulating case reports have attracted attention to the issue of dabigatran-induced esophagitis(DIE).[2,3]Recent studies have found that elderly patients are more likely to develop DIE.[4]However,herein,we present a case of a younger male who developed DIE after taking dabigatran.展开更多
基金supported by the National Key Research and Development Program of China (No. 2023YFC2206200)the National Natural Science Foundation of China (No.12375059)the Fundamental Research Funds for the Central Universities。
文摘The Weyl double copy builds the relation between gauge theory and gravity theory, in particular the correspondence between gauge solutions and gravity solutions. In this paper, we obtain the slowly rotating charge solutions from the Weyl double copy for the Kerr black hole with small Chern-Simons correction. Based on the Weyl double copy relation, for the Petrov type D solution in Chern-Simons modified gravity, we find the additional correction to the electromagnetic field strength tensor of the rotating charge. For the Petrov type I solution, we find that the additional electromagnetic field strength tensors have external sources, while the total sources vanish at the leading order.
文摘A high-performance vibration isolation platform （VIP） has been developed for a cluster of control moment gyroscopes （CMGs）. CMGs have long been used for satellite attitude control. In this paper, the influence of flexible solar arrays on a passive multi-strut VIP of CMGs for a satellite is analyzed. The reasonable parameters design of flexi- ble solar arrays is discussed. Firstly, the dynamic model of the integrated satellite with flexible solar arrays, the VIP and CMGs is conducted by Newton-Euler method. Then based on reasonable assumptions, the transmissibility matrix of the VIP is derived. Secondly, the influences of the flexible solar arrays on both the performance of the VIP and the stability of closed-loop control systems are analyzed in detail. The parameter design limitation of these solar arrays is discussed. At last, by selecting reasonable parameters for both the VIP and flexible solar arrays, the attitude stabilization performance with vibration isolation system is predicted via simulation.
基金supported by the Excellent Young Scholars Research Fund of Beijing Institute of Technology(2012YG0101)the National Natural Science Foundation of China(11302026)
文摘In remote sensing or laser communication space missions, spacecraft need fast maneuver and fast stabilization in order to accomplish agile imaging and attitude tracking tasks. However, fast attitude maneuvers can easily cause elastic deformations and vibrations in flexible appendages of the spacecraft. This paper focuses on this problem and deals with the combined control of fast attitude maneuver and sta- bilization for large complex spacecraft. The mathematical model of complex spacecraft with flexible appendages and momentum bias actuators on board is presented. Based on the plant model and combined with the feedback controller, modal parameters of the closed-loop system are calculated, and a multiple mode input shaper utilizing the modal information is designed to suppress vibrations. Aiming at reducing vibrations excited by attitude maneuver, a quintic polynomial form rotation path planning is proposed with constraints on the actuators and the angular velocity taken into account. Attitude maneuver simulation results of the control systems with input shaper or path planning in loop are sepa- rately analyzed, and based on the analysis, a combined control strategy is presented with both path planning and input shaper in loop. Simulation results show that the combined control strategy satisfies the complex spacecraft＇s require- ment of fast maneuver and stabilization with the actuators＇ torque limitation satisfied at the same time.
文摘BACKGROUND Patients with atrial fibrillation(AF)and prior stroke history have a high risk of cardiovascular events despite anticoagulation therapy.It is unclear whether catheter ablation(CA)has further benefits in these patients.METHODS AF patients with a previous history of stroke or systemic embolism(SE)from the prospective Chinese Atrial Fibrillation Registry study between August 2011 and December 2020 were included in the analysis.Patients were matched in a 1:1 ratio to CA or medical treatment(MT)based on propensity score.The primary outcome was a composite of all-cause death or ischemic stroke(IS)/SE.RESULTS During a total of 4.1±2.3 years of follow-up,the primary outcome occurred in 111 patients in the CA group(3.3 per 100 person-years)and in 229 patients in the MT group(5.7 per 100 person-years).The CA group had a lower risk of the primary outcome compared to the MT group[hazard ratio(HR)=0.59,95%CI:0.47–0.74,P<0.001].There was a significant decreasing risk of all-cause mortality(HR=0.43,95%CI:0.31–0.61,P<0.001),IS/SE(HR=0.73,95%CI:0.54–0.97,P=0.033),cardiovascular mortality(HR=0.32,95%CI:0.19–0.54,P<0.001)and AF recurrence(HR=0.33,95%CI:0.30–0.37,P<0.001)in the CA group compared to that in the MT group.Sensitivity analysis generated consistent results when adjusting for time-dependent usage of anticoagulants.CONCLUSIONS In AF patients with a prior stroke history,CA was associated with a lower combined risk of all-cause death or IS/SE.Further clinical trials are warranted to confirm the benefits of CA in these patients.
基金supported by the Natural Science Foundation of Nanjing University of Posts and Telecommunications(NY222157,NY221085)State Key Laboratory of Organic Electronics and Information Display(GZR2022010008)+5 种基金Key Laboratory of Low-dimensional Materials Chemistry of Jiangsu Province(JSKC20022)General Program of China Postdoctoral Science Foundation(2022M711684)General Program of Basic Science(Natural Science)of Colleges and Universities of Jiangsu Province(22KJB430036)National Overseas Study Fund(202008320051)National Key Laboratory(2009DS690095)the National Natural Science Foundation of China(62288102).
文摘Stability against oxygen is an important factor affecting the performance of organic semiconductor devices.Improving photooxidation stability can prolong the service life of the device and maintain the mechanical and photoelectric properties of the device.Generally,various encapsulation methods from molecular structure to macroscopic device level are used to improve photooxidation stability.Here,we adopted a crystallization strategy to allow 14H-spiro[dibenzo[c,h]acridine-7,9′-fluorene](SFDBA)to pack tightly to resist fluorescence decay caused by oxidation.In this case,the inert group of SFDBA acts as a“steric armor”,protecting the photosensitive group from being attacked by oxygen.Therefore,compared with the fluorescence quenching of SFDBA powder under 2 h of sunlight,SFDBA crystal can maintain its fluorescence emission for more than 8 h under the same conditions.Furthermore,the photoluminescence quantum yields(PLQYs)of the crystalline film is 327%higher than that of the amorphous film.It shows that the crystallization strategy is an effective method to resist oxidation.
基金This study was supported by Grants from the National Natural Science Foundation of China(No.81700271)S&T Program of Hebei(No.H2018105054)the China Postdoctoral Science Foundation(2018M641418)the Beijing Postdoctoral Research Foundation(No.2018-22-107)。
文摘To the Editor:Atrial fibrillation(AF)is one of the leading risk factors for stroke and is associated with a fivefold increase in the incidence of stroke.For years,warfarin has been prescribed to lower the thrombotic risk in patients with AF.However,because of the finicky nature of warfarin(ie,unpredictable pharmacokinetics,frequent international normalized ratio testing,complex food-drug interactions,etc.),it has been incrementally replaced by multiple direct oral anticoagulants(DOACs).Dabigatran,a potent,competitive,and reversible DOAC that directly targets thrombin,was approved by the US Food and Drug Administration in 2010 as an alternative antithrombotic option for nonvalvular AF.While the randomized evaluation of long-term anticoagulation therapy(RE-LY)trial(a noninferiority trial comparing warfarin with dabigatran in patients with AF)showed that dabigatran is as successful as warfarin for preventing stroke or systemic embolism,its adverse effects also need attention.[1]Accumulating case reports have attracted attention to the issue of dabigatran-induced esophagitis(DIE).[2,3]Recent studies have found that elderly patients are more likely to develop DIE.[4]However,herein,we present a case of a younger male who developed DIE after taking dabigatran.
