Objective The purpose of this study was to compare remote magnetic catheter navigation with manual navigation for the ablation of atrioventricular nodal reentry tachycardia (AVNRT). Methods From November 2007 to Nov...Objective The purpose of this study was to compare remote magnetic catheter navigation with manual navigation for the ablation of atrioventricular nodal reentry tachycardia (AVNRT). Methods From November 2007 to November 2009, 30 consecutive patients with AVNRT received radiofrequency ablation in the Institute of Geriatric Cardiology. Of them, 14 were treated with remote magnetic navigation (RMN) and 16 with manual catheter navigation (MCN). Total fluoroscopic time,procedure time, procedural success rate, and complication rate were compared between the two groups. Results Total fluoroscopy time and precise orientation time were reduced in RMN group compared to MCN group (7.5+0.3 min vs 13.9~5.3 rain, and 1.0-x-0.3 min vs 3.2:~0.6 min, respectively, both P〈0.05). Procedural success rates in both groups were 100% and no AVNRT recurred in all patients during 3 months' follow-up. The number of lesions delivered was less for RMN group (3.4~1.1 vs 6.3+2.2, P〈0.05). Total procedure time (25.6~7.5 rain vs 27.5a:6.2 rain,/〉〉0.05) was similar between the 2 groups. No procedural complications occurred in both groups. Conclusions RMN for mapping and ablation of AVNRT significantly reduce precise orientation time, total fluoroscopy time and number of lesions delivered compared to the conventional technique of manual steering of deflectable catheters. Remote magnetic control mapping and ablation of AVNRT is more safe and feasible (J Geriatr Cardio12010; 7:7-9).展开更多
Green fluorescent protein (GFP) and its variants /homolog proteins are generally called as GFP-like fluorescent proteins (FPs), which are widely used as visible molecular tools for monitoring a wide range of biologica...Green fluorescent protein (GFP) and its variants /homolog proteins are generally called as GFP-like fluorescent proteins (FPs), which are widely used as visible molecular tools for monitoring a wide range of biological processes due to their capability of simple, accurate and real time quantification. The FPs-based molecular and visible quantification tools are giving more impact on bioprocess engineering, enabling the biomolecule-level dynamic information to be linked with the process-level events. In this review, different applications of FPs in biological engineering with emphasis on rapid molecular bioprocess quantification, such as quantification of the transcription efficiency, the protein production, the protein folding efficiency, the cell concentration, the intracellular microenvironments and so on, would be first introduced. The challenges of using FPs with respect to actual bioprocess applications for the precise quantification including the interaction of FPs and the fused partner proteins, the maturation of FPs, the inner filter effect and sensing technology were then discussed. Finally, the future development for the FPs used in molecular bioprocess quantification would be proposed.展开更多
Long PN-code acquisition is a difficult and time-consuming task due to long code period.To accelerate acquisition,folding methods like XFAST are widely used.In highdynamic environment however,the application of those ...Long PN-code acquisition is a difficult and time-consuming task due to long code period.To accelerate acquisition,folding methods like XFAST are widely used.In highdynamic environment however,the application of those methods are largely restricted due to nonnegligible residual frequency.This paper proposes a new dual-channel method for fast acquisition of long PN-code.In the proposed method,both non-overlapping local PNcode blocks are employed to correlate with input sample block;the detection process is eased through finding the maximum value among correlation results and verification is made with all the full and partial peaks taken into account.False alarm probabilities from analysis of the verification process are derived.Both theoretical and Monte Carlo simulations reveal that,with respect to acquisition probability and mean acquisition time under the same false alarm rate,dual-channel method has advantage over zero-padding and XFAST based folding methods under certain false alarm probabilities.展开更多
In this study, we apply both palrwise AMBER03 force field and the recently developed polarized force field to study the folding process of EK peptide under various ion strength and pH conditions. The polarized force f...In this study, we apply both palrwise AMBER03 force field and the recently developed polarized force field to study the folding process of EK peptide under various ion strength and pH conditions. The polarized force field is based on our newly proposed adaptive hydrogen bond-specific charge (AHBC) scheme. These two force fields differ only by the atomic charges. Solvent effect is described with generalized Born models (IGB5 in AMBER 10 package). The result shows that although when applying AMBER03 charge, the helical structure is preferred, its dependence on salt concentration and pH is qualitatively wrong. While using AHBC the peptide finds its native structure within 10 ns, and then fluctuates around this folded state. Under high salt concentration or extreme pH conditions the calculated helical structure probability drops, which is in qualitative agreement with the experiment. Analysis of the atomic charges and the interaction between the donor-acceptor pair in main hydrogen bonds shows that the helical structure is stabilized when polarization effect is counted. It again shows that polarization effect is a very important improvement over traditional force field and is essential for protein folding. We also prove that the salt bridge interaction between 4-residue apart GLU and LYS residues is not critical to the stability of helical structure of EK peptide, but is merely an auxiliary factor, also in agreement with the experiment.展开更多
Using molecular dynamics (MD) simulations, we have investigated the kinetics of the graphene edge folding process. The lower limit of the energy barrier is found to be -380 meV/A (or about 800 meV per edge atom) a...Using molecular dynamics (MD) simulations, we have investigated the kinetics of the graphene edge folding process. The lower limit of the energy barrier is found to be -380 meV/A (or about 800 meV per edge atom) and -50 meV/A (or about 120 meV per edge atom) for folding the edges of intrinsic clean single-layer graphene (SLG) and double-layer graphene (DLG), respectively. However, the edge folding barriers can be substantially reduced by imbalanced chemical adsorption, such as of H atoms, on the two sides of graphene along the edges. Our studies indicate that thermal folding is not feasible at room temperature (RT) for clean SLG and DLG edges and is feasible at high temperature only for DLG edges, whereas chemical folding (with adsorbates) of both SLG and DLG edges can be spontaneous at RT. These findings suggest that the folded edge structures of suspended graphene observed in some experiments are possibly due to the presence of adsorbates at the edges.展开更多
Sterols and triterpenes are structurally diverse bioactive molecules generated through cyclization of linear 2,3-oxidosqualene. Based on carbocationic intermediates generated during initial substrate preorganization s...Sterols and triterpenes are structurally diverse bioactive molecules generated through cyclization of linear 2,3-oxidosqualene. Based on carbocationic intermediates generated during initial substrate preorganization step, oxidosqualene cyclases (OSCs) are roughly segregated into protosteryl cation group that mainly catalyzes tetracyclic products and dammarenyl cation group which mostly generates pentacyclic products. However, in contrast to well-studied cascade of ring-forming reactions, little is known about the mechanism underlying the initial sub- strate folding process. Previously, we have identified a cucurbitadienol synthase (Bi) and its null allele bi (C393Y) from cucumber. By integration of homology modeling, residue coevolution and site-directed mutagenesis, we discover that four covarying amino acids including C393 constitute a dynamic domain that may be involved in substrate folding process for Bi. We also reveal a group of co-conserved residues that closely associated with the segregation of plant OSCs. These residues may act col- laboratively in choice of specific substrate folding inter- mediate for OSCs. Thus, engineer plant OSCs from into five-ringed producer. our findings open a door to four-ringed skeleton catalysts展开更多
The Cenozoic basin offshore the Bohai Sea underwent a multicycle-rifting during its evolutionary process, which resulted in the multiple unconformities in the strata. The tectonic activities shown by these unconformit...The Cenozoic basin offshore the Bohai Sea underwent a multicycle-rifting during its evolutionary process, which resulted in the multiple unconformities in the strata. The tectonic activities shown by these unconformities have different manifestations and influences on the basin evolution. The authors systematically analyze the tectonic evolution characteristics of the sags off-shore the Bohai Sea with a large set of hydrocarbon exploration data. The analysis reveals that two phases of tectonic activities during the late depositional stage of the third member of Shahejie Formation (about 38 Ma) and the late depositional stage of Dongying Formation (about 24 Ma) reflect the significant changes in the basin's features and structural framework before and after these tectonic activities. As a result, the two phases of tectonic activities are recognized as important turning points (i.e., tectonic transitions) of Cenozoic basin evolution. The regional dynamic backgrounds of the two phases of tectonic transitions are also discussed. It is suggested that the early tectonic transition occurred at about 38 Ma under such regional dynamic back- ground that a huge kinematics adjustment happened between Eurasian Plate and its neighboring plates, i.e., Pacific Plate and Indian Plate. Meanwhile, the Tan-Lu Fault's slip reversed from left lateral to right lateral. The late tectonic transition occurred in late Paleogene (about 24 Ma) and reflected the Himalayan orogeny's influence on the Chinese continent and even the Asian continent; at the same time, the stress field produced by the escape tectonics was related to the Himalayan orogeny, superposed on the pre-existing stress field, and then enhanced the right lateral slip activity of the Tan-Lu Fault.展开更多
Exploration of new infrared(IR) nonlinear optical(NLO) materials is still in urgency owing to the indispensable roles in optoelectronic devices, resource exploration, and long-distance laser communication. The formida...Exploration of new infrared(IR) nonlinear optical(NLO) materials is still in urgency owing to the indispensable roles in optoelectronic devices, resource exploration, and long-distance laser communication. The formidable challenge is to balance the contradiction between wide band gaps and large second harmonic generation(SHG) effects in IR NLO materials. In the present work, we proposed new kinds of NLO active units, d^0 transition metal fluorooxofunctional groups for designing mid-IR NLO materials. By studying a series of d^0 transition metal oxyfluorides(TMOFs),the influences of fluorooxo-functional groups with different d^0 configuration cations on the band gap and SHG responses were explored. The results reveal that the fluorooxo-functional groups with different d^0 configuration cations can enlarge band gaps in mid-IR NLO materials. The first-principles calculations demonstrate that the nine alkali/alkaline earth metals d^0 TMOFs exhibit wide band gaps(all the band gaps >3.0 e V), large birefringence Δn(> 0.07), and two W/Mo TMOFs also exhibit large SHG responses. Moreover, by comparing with other fluorooxo-functional groups, it is found that introducing fluorine into building units is an effective way to enhance optical performance. These d^0 TMOFs with superior fluorooxo-functional groups represent a new exploration family of the mid-IR region, which sheds light on the design of mid-IR NLO materials possessing large band gap.展开更多
Subclavian artery thrombosis is a rare complication of clavicle fractures. We reported a 20-yearold man who was admitted to the emergency room after a road traffic accident. He was a pedestrian who was initially hit b...Subclavian artery thrombosis is a rare complication of clavicle fractures. We reported a 20-yearold man who was admitted to the emergency room after a road traffic accident. He was a pedestrian who was initially hit by a bus and after he fell down on the road, he was run over by a car. On evaluation, he was found to have multiple facial and rib fractures, distal fight humerus and right clavicle fracture. Significantly, right radial pulse was absent. After further evaluation including Doppler studies and an angiography which revealed complete obstruction of right subclavian artery just distal to its 1 st portion, the patient was urgently taken to the operation room. A midclavicular fracture was adjacent to the injured vessel. We established proximal and distal control, removed damaged part. After mobilizing the subclavian artery, an end-to-end anastomosis was made. Then open reduction and internal fixation of right distal humerus was performed. The rest of the postoperative course was unremarkable. To prevent complications of subclavian artery thrombosis, different treatment modalities can be used, including anticoagulation therapy, angioplasty, stenting and bypass procedures.展开更多
Biological world always provides inspirations for engineering designs, and insects are important targets to mimic. For the Coleoptera, its flight has been emphasized for long. However, the invisible folding procedure ...Biological world always provides inspirations for engineering designs, and insects are important targets to mimic. For the Coleoptera, its flight has been emphasized for long. However, the invisible folding procedure of hind wings, which occurs under the stiff elytra after flight, still remains unknown. In this paper, the wing folding process and the surficial microstructures of elytra, hind wing and abdomen are investigated by video recording and scanning electron microscopy. The results show that there are hooklike protrusions approximately 15 μm in length distributing on the inner side of elytra, and bump-like protrusions on the hind wings. The 'hooks' may anchor the 'bumps' on the main wing to prevent corrugation during folding. The horizontal protrusions observed on the abdomen shape a hairy cuticle, which is conducive to a better wing-abdomen interaction. Thus, the ratcheting mechanism that wing folding facilitated by micro-protrusions on the body surface is revealed. This new finding helps us to further understand the functions of diversely shaped protrusions in the physiology of insects. More importantly, the ratcheting mechanism could serve as a cuticle interaction model and inspire new engineering applications, such as microsystems.展开更多
This paper studies the strong n(n =—1,0)-discount and finite horizon criteria for continuoustime Markov decision processes in Polish spaces.The corresponding transition rates are allowed to be unbounded,and the rewar...This paper studies the strong n(n =—1,0)-discount and finite horizon criteria for continuoustime Markov decision processes in Polish spaces.The corresponding transition rates are allowed to be unbounded,and the reward rates may have neither upper nor lower bounds.Under mild conditions,the authors prove the existence of strong n(n =—1,0)-discount optimal stationary policies by developing two equivalence relations:One is between the standard expected average reward and strong—1-discount optimality,and the other is between the bias and strong 0-discount optimality.The authors also prove the existence of an optimal policy for a finite horizon control problem by developing an interesting characterization of a canonical triplet.展开更多
文摘Objective The purpose of this study was to compare remote magnetic catheter navigation with manual navigation for the ablation of atrioventricular nodal reentry tachycardia (AVNRT). Methods From November 2007 to November 2009, 30 consecutive patients with AVNRT received radiofrequency ablation in the Institute of Geriatric Cardiology. Of them, 14 were treated with remote magnetic navigation (RMN) and 16 with manual catheter navigation (MCN). Total fluoroscopic time,procedure time, procedural success rate, and complication rate were compared between the two groups. Results Total fluoroscopy time and precise orientation time were reduced in RMN group compared to MCN group (7.5+0.3 min vs 13.9~5.3 rain, and 1.0-x-0.3 min vs 3.2:~0.6 min, respectively, both P〈0.05). Procedural success rates in both groups were 100% and no AVNRT recurred in all patients during 3 months' follow-up. The number of lesions delivered was less for RMN group (3.4~1.1 vs 6.3+2.2, P〈0.05). Total procedure time (25.6~7.5 rain vs 27.5a:6.2 rain,/〉〉0.05) was similar between the 2 groups. No procedural complications occurred in both groups. Conclusions RMN for mapping and ablation of AVNRT significantly reduce precise orientation time, total fluoroscopy time and number of lesions delivered compared to the conventional technique of manual steering of deflectable catheters. Remote magnetic control mapping and ablation of AVNRT is more safe and feasible (J Geriatr Cardio12010; 7:7-9).
基金Supported by the National Natural Science Foundation of China (20836004 20806046) the Special Fund for Major State Basic Research Program of China (2009CB724702) the National High Technology Research and Development Program ofChina (2009AA062903)
文摘Green fluorescent protein (GFP) and its variants /homolog proteins are generally called as GFP-like fluorescent proteins (FPs), which are widely used as visible molecular tools for monitoring a wide range of biological processes due to their capability of simple, accurate and real time quantification. The FPs-based molecular and visible quantification tools are giving more impact on bioprocess engineering, enabling the biomolecule-level dynamic information to be linked with the process-level events. In this review, different applications of FPs in biological engineering with emphasis on rapid molecular bioprocess quantification, such as quantification of the transcription efficiency, the protein production, the protein folding efficiency, the cell concentration, the intracellular microenvironments and so on, would be first introduced. The challenges of using FPs with respect to actual bioprocess applications for the precise quantification including the interaction of FPs and the fused partner proteins, the maturation of FPs, the inner filter effect and sensing technology were then discussed. Finally, the future development for the FPs used in molecular bioprocess quantification would be proposed.
文摘Long PN-code acquisition is a difficult and time-consuming task due to long code period.To accelerate acquisition,folding methods like XFAST are widely used.In highdynamic environment however,the application of those methods are largely restricted due to nonnegligible residual frequency.This paper proposes a new dual-channel method for fast acquisition of long PN-code.In the proposed method,both non-overlapping local PNcode blocks are employed to correlate with input sample block;the detection process is eased through finding the maximum value among correlation results and verification is made with all the full and partial peaks taken into account.False alarm probabilities from analysis of the verification process are derived.Both theoretical and Monte Carlo simulations reveal that,with respect to acquisition probability and mean acquisition time under the same false alarm rate,dual-channel method has advantage over zero-padding and XFAST based folding methods under certain false alarm probabilities.
基金supported by the National Natural Science Foundation of China (20803034)the Shanghai Rising-Star Program+2 种基金supported by the Nanyang Technological University Start-up (M58110043)support from the National Natural Science Foundation of China (20933002)Shanghai Pujiang Program (09PJ1404000)
文摘In this study, we apply both palrwise AMBER03 force field and the recently developed polarized force field to study the folding process of EK peptide under various ion strength and pH conditions. The polarized force field is based on our newly proposed adaptive hydrogen bond-specific charge (AHBC) scheme. These two force fields differ only by the atomic charges. Solvent effect is described with generalized Born models (IGB5 in AMBER 10 package). The result shows that although when applying AMBER03 charge, the helical structure is preferred, its dependence on salt concentration and pH is qualitatively wrong. While using AHBC the peptide finds its native structure within 10 ns, and then fluctuates around this folded state. Under high salt concentration or extreme pH conditions the calculated helical structure probability drops, which is in qualitative agreement with the experiment. Analysis of the atomic charges and the interaction between the donor-acceptor pair in main hydrogen bonds shows that the helical structure is stabilized when polarization effect is counted. It again shows that polarization effect is a very important improvement over traditional force field and is essential for protein folding. We also prove that the salt bridge interaction between 4-residue apart GLU and LYS residues is not critical to the stability of helical structure of EK peptide, but is merely an auxiliary factor, also in agreement with the experiment.
文摘Using molecular dynamics (MD) simulations, we have investigated the kinetics of the graphene edge folding process. The lower limit of the energy barrier is found to be -380 meV/A (or about 800 meV per edge atom) and -50 meV/A (or about 120 meV per edge atom) for folding the edges of intrinsic clean single-layer graphene (SLG) and double-layer graphene (DLG), respectively. However, the edge folding barriers can be substantially reduced by imbalanced chemical adsorption, such as of H atoms, on the two sides of graphene along the edges. Our studies indicate that thermal folding is not feasible at room temperature (RT) for clean SLG and DLG edges and is feasible at high temperature only for DLG edges, whereas chemical folding (with adsorbates) of both SLG and DLG edges can be spontaneous at RT. These findings suggest that the folded edge structures of suspended graphene observed in some experiments are possibly due to the presence of adsorbates at the edges.
基金supported by funding from the National Natural Science Foundation of China (31401886)the Agricultural Science and Technology Innovation Program
文摘Sterols and triterpenes are structurally diverse bioactive molecules generated through cyclization of linear 2,3-oxidosqualene. Based on carbocationic intermediates generated during initial substrate preorganization step, oxidosqualene cyclases (OSCs) are roughly segregated into protosteryl cation group that mainly catalyzes tetracyclic products and dammarenyl cation group which mostly generates pentacyclic products. However, in contrast to well-studied cascade of ring-forming reactions, little is known about the mechanism underlying the initial sub- strate folding process. Previously, we have identified a cucurbitadienol synthase (Bi) and its null allele bi (C393Y) from cucumber. By integration of homology modeling, residue coevolution and site-directed mutagenesis, we discover that four covarying amino acids including C393 constitute a dynamic domain that may be involved in substrate folding process for Bi. We also reveal a group of co-conserved residues that closely associated with the segregation of plant OSCs. These residues may act col- laboratively in choice of specific substrate folding inter- mediate for OSCs. Thus, engineer plant OSCs from into five-ringed producer. our findings open a door to four-ringed skeleton catalysts
基金supported by the Important National Science & Technology Specific Project (Grant No. 2011ZX05023)
文摘The Cenozoic basin offshore the Bohai Sea underwent a multicycle-rifting during its evolutionary process, which resulted in the multiple unconformities in the strata. The tectonic activities shown by these unconformities have different manifestations and influences on the basin evolution. The authors systematically analyze the tectonic evolution characteristics of the sags off-shore the Bohai Sea with a large set of hydrocarbon exploration data. The analysis reveals that two phases of tectonic activities during the late depositional stage of the third member of Shahejie Formation (about 38 Ma) and the late depositional stage of Dongying Formation (about 24 Ma) reflect the significant changes in the basin's features and structural framework before and after these tectonic activities. As a result, the two phases of tectonic activities are recognized as important turning points (i.e., tectonic transitions) of Cenozoic basin evolution. The regional dynamic backgrounds of the two phases of tectonic transitions are also discussed. It is suggested that the early tectonic transition occurred at about 38 Ma under such regional dynamic back- ground that a huge kinematics adjustment happened between Eurasian Plate and its neighboring plates, i.e., Pacific Plate and Indian Plate. Meanwhile, the Tan-Lu Fault's slip reversed from left lateral to right lateral. The late tectonic transition occurred in late Paleogene (about 24 Ma) and reflected the Himalayan orogeny's influence on the Chinese continent and even the Asian continent; at the same time, the stress field produced by the escape tectonics was related to the Himalayan orogeny, superposed on the pre-existing stress field, and then enhanced the right lateral slip activity of the Tan-Lu Fault.
基金supported by Tianshan Innovation Team Program (2018D14001)the National Natural Science Foundation of China (51922014 and 11774414)+2 种基金Shanghai Cooperation Organization Science and Technology Partnership Program (2017E01013)Xinjiang Program of Introducing High-Level Talents, Fujian Institute of Innovation, Chinese Academy of Sciences (FJCXY18010202)the Western Light Foundation of CAS (2017-XBQNXZ-B-006 and 2016QNXZ-B-9)
文摘Exploration of new infrared(IR) nonlinear optical(NLO) materials is still in urgency owing to the indispensable roles in optoelectronic devices, resource exploration, and long-distance laser communication. The formidable challenge is to balance the contradiction between wide band gaps and large second harmonic generation(SHG) effects in IR NLO materials. In the present work, we proposed new kinds of NLO active units, d^0 transition metal fluorooxofunctional groups for designing mid-IR NLO materials. By studying a series of d^0 transition metal oxyfluorides(TMOFs),the influences of fluorooxo-functional groups with different d^0 configuration cations on the band gap and SHG responses were explored. The results reveal that the fluorooxo-functional groups with different d^0 configuration cations can enlarge band gaps in mid-IR NLO materials. The first-principles calculations demonstrate that the nine alkali/alkaline earth metals d^0 TMOFs exhibit wide band gaps(all the band gaps >3.0 e V), large birefringence Δn(> 0.07), and two W/Mo TMOFs also exhibit large SHG responses. Moreover, by comparing with other fluorooxo-functional groups, it is found that introducing fluorine into building units is an effective way to enhance optical performance. These d^0 TMOFs with superior fluorooxo-functional groups represent a new exploration family of the mid-IR region, which sheds light on the design of mid-IR NLO materials possessing large band gap.
文摘Subclavian artery thrombosis is a rare complication of clavicle fractures. We reported a 20-yearold man who was admitted to the emergency room after a road traffic accident. He was a pedestrian who was initially hit by a bus and after he fell down on the road, he was run over by a car. On evaluation, he was found to have multiple facial and rib fractures, distal fight humerus and right clavicle fracture. Significantly, right radial pulse was absent. After further evaluation including Doppler studies and an angiography which revealed complete obstruction of right subclavian artery just distal to its 1 st portion, the patient was urgently taken to the operation room. A midclavicular fracture was adjacent to the injured vessel. We established proximal and distal control, removed damaged part. After mobilizing the subclavian artery, an end-to-end anastomosis was made. Then open reduction and internal fixation of right distal humerus was performed. The rest of the postoperative course was unremarkable. To prevent complications of subclavian artery thrombosis, different treatment modalities can be used, including anticoagulation therapy, angioplasty, stenting and bypass procedures.
基金supported by the National Natural Science Foundation of China(51176087)
文摘Biological world always provides inspirations for engineering designs, and insects are important targets to mimic. For the Coleoptera, its flight has been emphasized for long. However, the invisible folding procedure of hind wings, which occurs under the stiff elytra after flight, still remains unknown. In this paper, the wing folding process and the surficial microstructures of elytra, hind wing and abdomen are investigated by video recording and scanning electron microscopy. The results show that there are hooklike protrusions approximately 15 μm in length distributing on the inner side of elytra, and bump-like protrusions on the hind wings. The 'hooks' may anchor the 'bumps' on the main wing to prevent corrugation during folding. The horizontal protrusions observed on the abdomen shape a hairy cuticle, which is conducive to a better wing-abdomen interaction. Thus, the ratcheting mechanism that wing folding facilitated by micro-protrusions on the body surface is revealed. This new finding helps us to further understand the functions of diversely shaped protrusions in the physiology of insects. More importantly, the ratcheting mechanism could serve as a cuticle interaction model and inspire new engineering applications, such as microsystems.
基金supported by the National Natural Science Foundation of China under Grant Nos.61374080 and 61374067the Natural Science Foundation of Zhejiang Province under Grant No.LY12F03010+1 种基金the Natural Science Foundation of Ningbo under Grant No.2012A610032Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘This paper studies the strong n(n =—1,0)-discount and finite horizon criteria for continuoustime Markov decision processes in Polish spaces.The corresponding transition rates are allowed to be unbounded,and the reward rates may have neither upper nor lower bounds.Under mild conditions,the authors prove the existence of strong n(n =—1,0)-discount optimal stationary policies by developing two equivalence relations:One is between the standard expected average reward and strong—1-discount optimality,and the other is between the bias and strong 0-discount optimality.The authors also prove the existence of an optimal policy for a finite horizon control problem by developing an interesting characterization of a canonical triplet.