我们采用Brenner and Izhakian(2018)基于期望效用模型(EUUP)构建的实证模糊性指标,分析了上证综指代表的中国股票市场中风险、模糊性和股市收益率的关系。研究发现,基于月度数据,模糊性在中国股市中被定价,并且其对于风险资产收益率的...我们采用Brenner and Izhakian(2018)基于期望效用模型(EUUP)构建的实证模糊性指标,分析了上证综指代表的中国股票市场中风险、模糊性和股市收益率的关系。研究发现,基于月度数据,模糊性在中国股市中被定价,并且其对于风险资产收益率的解释效果远优于风险。市场模糊性溢价水平和市场有利概率有密切关系,实证结果和已有行为研究的发现以及理论预期相符。中国股市的有利概率临界概率点约为45%,略低于美国股市,表明中国投资者对模糊性更加担忧,要求的模糊性溢价更高。依据对实证数据的进一步分析,我们发现EUUP构建的模糊性测度面临两个潜在问题,并对其进行了讨论和提出了建议。同时发现本文模糊性指标和中国经济政策不确定性指标存在正相关关系,但与具体政策领域的不确定性指标不具有相关关系。展开更多
Owing to the merits of low cost,high safety and environmental benignity,rechargeable aqueous Zn-based batteries(ZBs)have gained tremendous attention in recent years.Nevertheless,the poor reversibility of Zn anodes tha...Owing to the merits of low cost,high safety and environmental benignity,rechargeable aqueous Zn-based batteries(ZBs)have gained tremendous attention in recent years.Nevertheless,the poor reversibility of Zn anodes that originates from dendrite growth,surface passivation and corrosion,severely hinders the further development of ZBs.To tackle these issues,here we report a Janus separator based on a Zn-ion conductive metal-organic framework(MOF)and reduced graphene oxide(rGO),which is able to regulate uniform Zn2+flux and electron conduction simultaneously during battery operation.Facilitated by the MOF/rGO bifunctional interlayers,the Zn anodes demonstrate stable plating/stripping behavior(over 500 h at 1 mA cm^(−2)),high Coulombic efficiency(99.2%at 2 mA cm^(−2) after 100 cycles)and reduced redox barrier.Moreover,it is also found that the Zn corrosion can be effectively retarded through diminishing the potential discrepancy on Zn surface.Such a separator engineering also saliently promotes the overall performance of Zn|MnO2 full cells,which deliver nearly 100%capacity retention after 2000 cycles at 4 A g^(−1) and high power density over 10 kW kg^(−1).This work provides a feasible route to the high-performance Zn anodes for ZBs.展开更多
As the depth and horizontal length of shale gas development wells increase,the requirement for the temperature resistance and the ability of the drilling fluids to stabilize the shale formation becomes higher.A new ty...As the depth and horizontal length of shale gas development wells increase,the requirement for the temperature resistance and the ability of the drilling fluids to stabilize the shale formation becomes higher.A new type of high temperature and high density white oil based drilling fluid system has been developed in laboratory.Research shows that the drilling fluid system has good rheological property,low filtration loss,strong anti-debris pollution capability and good plugging performance at high temperature and high density.The system has been successfully applied in the 201H7-6 well.Application results show that the drilling fluid rheology,high temperature and high pressure fluid loss and demulsification voltage meet the field requirements.The drilling fluid performance is stable in drilling an 1800 m horizontal section,and no stuck or shale swelling and wellbore collapsing are induced.It is the first well drilled successfully with domestic white oil-based drilling fluid in Zigong Region.It also sets several new records including the deepest well,the shortest drilling cycle,and the fastest drilling speed in that region,which provides valuable experience for the future drilling activities.展开更多
Aiming at the problems of microfracture development in hard brittle shale gas layer in Fuling block, Chongqing, such as collapse of borehole wall and the existence of permeability loss of microfracture during drilling...Aiming at the problems of microfracture development in hard brittle shale gas layer in Fuling block, Chongqing, such as collapse of borehole wall and the existence of permeability loss of microfracture during drilling, and serious pollution of drilling environment with oil-based drilling fluid, a water-based drilling fluid system for anti-collapse and anti-leakage was studied. A water-based drilling fluid system with anti-collapse and anti-leakage was formed by introducing functional treatment agents, such as polypolysaccharide MEG, polymer emulsion film forming wall cementing agent LFGB, polyamine inhibitor LCFA and deformable particle plugging agent BXLZ, into the conventional water-based drilling fluid. After rolling at 130°C for 16 h, the system has good rheological properties, low filtration loss, good inhibition, lubrication and plugging properties. It has good plugging properties for 0.12 mm, 0.24 mm, 0.38 mm micro-cracks and 400 mD and 800 mD sand plates. The system was successfully tested on site in August 2019 in Fuling Reef Block, showing good rheological properties, solid wall plugging, and strong ability to seal and inhibit fracture expansion. There was no block falling in the drilling process, and the tripping, casing running and well cementing operations were all smooth, which provided a new technical idea and scheme for environmental protection and green drilling in Fuling shale gas exploitation.展开更多
Cellular heterogeneity is a universal property of living systems,and the interrogation of single cells facilitates in-depth understanding of distinct cellular states and functions in various biological processes.Co-an...Cellular heterogeneity is a universal property of living systems,and the interrogation of single cells facilitates in-depth understanding of distinct cellular states and functions in various biological processes.Co-analysis of transcripts and proteins from the same single cells opens the way to decipher complex RNA regulatory frameworks and phenotypes,facilitating the understanding of cellular fate and function regulations,discovery of novel cell types,and construction of a high-resolution cell atlas.Herein,we review the state-of-art advances in the development of methodologies for co-analysis of single-cell transcripts and proteins.First,imaging-based methods are summarized with particular emphasis on optical and mass spectrometry imaging.Next,sequencing-based approaches for high-throughput and sensitive co-analysis of single-cell transcripts and proteins are described,including droplet-,microwell-,and split-pool-based platforms.Subsequently,combined methods with more flexibility and universality are discussed.These methods commonly employ different strategies or reactions to convert transcripts and proteins of single cells into distinct signals simultaneously,which can be detected by different instruments or platforms.Lastly,some perspectives on the future challenges and development trends in this field are presented.展开更多
This article provides a review on X-ray pulsar-based navigation(XNAV).The review starts with the basic concept of XNAV,and briefly introduces the past,present and future projects concerning XNAV.This paper focuses on ...This article provides a review on X-ray pulsar-based navigation(XNAV).The review starts with the basic concept of XNAV,and briefly introduces the past,present and future projects concerning XNAV.This paper focuses on the advances of the key techniques supporting XNAV,including the navigation pulsar database,the X-ray detection system,and the pulse time of arrival estimation.Moreover,the methods to improve the estimation performance of XNAV are reviewed.Finally,some remarks on the future development of XNAV are provided.展开更多
3-Methylindole(skatole)is regarded as one of the most offensive compounds in odor emission.Biodegradation is feasible for skatole removal but the functional species and genes responsible for skatole degradation remain...3-Methylindole(skatole)is regarded as one of the most offensive compounds in odor emission.Biodegradation is feasible for skatole removal but the functional species and genes responsible for skatole degradation remain enigmatic.In this study,an efficient aerobic skatole-degrading consortium was obtained.Rhodococcus and Pseudomonas were identified as the two major and active populations by integrated metagenomic and metatranscriptomic analyses.Bioinformatic analyses indicated that the skatole downstream degradation wasmainly via the catechol pathway,and upstream degradation was likely catalyzed by the aromatic ring-hydroxylating oxygenase and flavin monooxygenase.Genome binning and gene analyses indicated that Pseudomonas,Pseudoclavibacter,and Raineyella should cooperate with Rhodococcus for the skatole degradation process.Moreover,a pure strain Rhodococcus sp.DMU1 was successfully obtained which could utilize skatole as the sole carbon source.Complete genome sequencing showed that strain DMU1 was the predominant population in the consortium.Further crude enzyme and RT-qPCR assays indicated that strain DMU1 degraded skatole through the catechol ortho-cleavage pathway.Collectively,our results suggested that synergistic degradation of skatole in the consortium should be performed by diverse bacteria with Rhodococcus as the primary degrader,and the degradation mainly proceeded via the catechol pathway.展开更多
Background Socioeconomic status(SES)inequity was recognized as a driver of some certain infectious diseases.However,few studies evaluated the association between SES and the burden of overall infections,and even fewer...Background Socioeconomic status(SES)inequity was recognized as a driver of some certain infectious diseases.However,few studies evaluated the association between SES and the burden of overall infections,and even fewer identified preventable mediators.This study aimed to assess the association between SES and overall infectious diseases burden,and the potential roles of factors including lifestyle,environmental pollution,chronic disease history.Methods We included 401,009 participants from the UK Biobank(UKB)and defined the infection status for each participant according to their diagnosis records.Latent class analysis(LCA)was used to define SES for each participant.We further defined healthy lifestyle score,environment pollution score(EPS)and four types of chronic comorbidities.We used multivariate logistic regression to test the associations between the four above covariates and infectious diseases.Then,we performed the mediation and interaction analysis to explain the relationships between SES and other variables on infectious diseases.Finally,we employed seven types of sensitivity analyses,including considering the Townsend deprivation index as an area level SES variable,repeating our main analysis for some individual or composite factors and in some subgroups,as well as in an external data from the US National Health and Nutrition Examination Survey,to verify the main results.Results In UKB,60,771(15.2%)participants were diagnosed with infectious diseases during follow-up.Lower SES[odds ratio(OR)=1.5570]were associated with higher risk of overall infections.Lifestyle score mediated 2.9%of effects from SES,which ranged from 2.9 to 4.0%in different infection subtypes,while cardiovascular disease(CVD)mediated a proportion of 6.2%with a range from 2.1 to 6.8%.In addition,SES showed significant negative interaction with lifestyle score(OR=0.8650)and a history of cancer(OR=0.9096),while a significant synergy interaction was observed between SES and EPS(OR=1.0024).In subgroup analysis,we found that males and African(AFR)with lower SES showed much higher infection risk.Results from sensitivity and validation analyses showed relative consistent with the main analysis.Conclusions Low SES is shown to be an important risk factor for infectious disease,part of which may be mediated by poor lifestyle and chronic comorbidities.Efforts to enhance health education and improve the quality of living environment may help reduce burden of infectious disease,especially for people with low SES.展开更多
Maritime transports play a critical role in international trade and commerce.Massive vessels sailing around the world continuously generate vessel trajectory data that contain rich spatial–temporal patterns of vessel...Maritime transports play a critical role in international trade and commerce.Massive vessels sailing around the world continuously generate vessel trajectory data that contain rich spatial–temporal patterns of vessel navigations.Analyzing and understanding these patterns are valuable for maritime traffic surveillance and management.As essential techniques in complex data analysis and understanding,visualization and visual analysis have been widely used in vessel trajectory data analysis.This paper presents a literature review on the visualization and visual analysis of vessel trajectory data.First,we introduce commonly used vessel trajectory data sets and summarize main operations in vessel trajectory data preprocessing.Then,we provide a taxonomy of visualization and visual analysis of vessel trajectory data based on existing approaches and introduce representative works in details.Finally,we expound on the prospects of the remaining challenges and directions for future research.展开更多
To estimate the physical dose of skin and key organs in a case of overexposure during a cardiac interventional procedure.Methods The female patient aged 50 suffered from owerexposure during ardiac interventional thera...To estimate the physical dose of skin and key organs in a case of overexposure during a cardiac interventional procedure.Methods The female patient aged 50 suffered from owerexposure during ardiac interventional therapy in a hospital,Xinxiang city,Henan province,China in January 2020.The mesh-type phantom for the patient was constructed based on the adult mesh-type reference computational phantoms(MRCPs)released by the International Comission on Radiological Protection Publication 145 (ICRP145)and phantom deformation technology.Models of exposure scenario were constructed and simulated with particle and heavy ion transport code system(PHTTS)according to exposure conditions.Resuts:The maximum absorbed dose of key organs/tissues under iradiation in posteroanterior(PA)and 30°left anterior oblique directions(LOA)was 632.4 and 305.6 mGy,respectively.The let lung,heart,and left mammary gland received a larger dose under both iradiation conditions.The ratio of the absorbed dose with and without shielding was a lculated,and the relative difference in most organs was<1%between two directions.The iso-dose curve of the back skin revealed the ditribution of the absorbed dose(0.1-5.2 Gy).The dose estimate of key tssues/organs was higher than the conventional level,especially the local skin,up to 5.2 Gy.Concusions The interventional procedure in this ase resulted in a higher dose.Monte Carlo codes combined with the MRCPs can be employed to estimate physical dose to individuals in concrete irradia tion scenarios.展开更多
An accurate period is important to recover the pulse profile from a recorded photon event series of an X-ray pulsar and to estimate the pulse time of arrival,which is the measurement of X-ray pulsar navigation.Epoch f...An accurate period is important to recover the pulse profile from a recorded photon event series of an X-ray pulsar and to estimate the pulse time of arrival,which is the measurement of X-ray pulsar navigation.Epoch folding is a classical period estimation method in the time domain;however,its computational complexity grows as the number of trail periods increases.In order to reduce the computational complexity,this paper improves the fast folding algorithm through segment correlation and amplitude accumulation,which is based on the post-order traversal of a binary tree.Compared with epoch folding,the improved fast folding algorithm can achieve a similar accuracy at the cost of a lower computational burden.Compared with the original fast folding algorithm,the improved algorithm can be applied to detectors with a much smaller effective area.The performance of the method is investigated by simulation data and observation data from the Neutron star Interior Composition Explorer(NICER).展开更多
文摘我们采用Brenner and Izhakian(2018)基于期望效用模型(EUUP)构建的实证模糊性指标,分析了上证综指代表的中国股票市场中风险、模糊性和股市收益率的关系。研究发现,基于月度数据,模糊性在中国股市中被定价,并且其对于风险资产收益率的解释效果远优于风险。市场模糊性溢价水平和市场有利概率有密切关系,实证结果和已有行为研究的发现以及理论预期相符。中国股市的有利概率临界概率点约为45%,略低于美国股市,表明中国投资者对模糊性更加担忧,要求的模糊性溢价更高。依据对实证数据的进一步分析,我们发现EUUP构建的模糊性测度面临两个潜在问题,并对其进行了讨论和提出了建议。同时发现本文模糊性指标和中国经济政策不确定性指标存在正相关关系,但与具体政策领域的不确定性指标不具有相关关系。
基金This work was financially supported by Hong Kong Innovation&Technology Fund(ITS/031/18)National Key R&D Program of China(2016YFB0700600)+1 种基金Soft Science Research Project of Guangdong Province(2017B030301013)Shenzhen Science and Technology Research Grant(ZDSYS201707281026184).
文摘Owing to the merits of low cost,high safety and environmental benignity,rechargeable aqueous Zn-based batteries(ZBs)have gained tremendous attention in recent years.Nevertheless,the poor reversibility of Zn anodes that originates from dendrite growth,surface passivation and corrosion,severely hinders the further development of ZBs.To tackle these issues,here we report a Janus separator based on a Zn-ion conductive metal-organic framework(MOF)and reduced graphene oxide(rGO),which is able to regulate uniform Zn2+flux and electron conduction simultaneously during battery operation.Facilitated by the MOF/rGO bifunctional interlayers,the Zn anodes demonstrate stable plating/stripping behavior(over 500 h at 1 mA cm^(−2)),high Coulombic efficiency(99.2%at 2 mA cm^(−2) after 100 cycles)and reduced redox barrier.Moreover,it is also found that the Zn corrosion can be effectively retarded through diminishing the potential discrepancy on Zn surface.Such a separator engineering also saliently promotes the overall performance of Zn|MnO2 full cells,which deliver nearly 100%capacity retention after 2000 cycles at 4 A g^(−1) and high power density over 10 kW kg^(−1).This work provides a feasible route to the high-performance Zn anodes for ZBs.
文摘As the depth and horizontal length of shale gas development wells increase,the requirement for the temperature resistance and the ability of the drilling fluids to stabilize the shale formation becomes higher.A new type of high temperature and high density white oil based drilling fluid system has been developed in laboratory.Research shows that the drilling fluid system has good rheological property,low filtration loss,strong anti-debris pollution capability and good plugging performance at high temperature and high density.The system has been successfully applied in the 201H7-6 well.Application results show that the drilling fluid rheology,high temperature and high pressure fluid loss and demulsification voltage meet the field requirements.The drilling fluid performance is stable in drilling an 1800 m horizontal section,and no stuck or shale swelling and wellbore collapsing are induced.It is the first well drilled successfully with domestic white oil-based drilling fluid in Zigong Region.It also sets several new records including the deepest well,the shortest drilling cycle,and the fastest drilling speed in that region,which provides valuable experience for the future drilling activities.
文摘Aiming at the problems of microfracture development in hard brittle shale gas layer in Fuling block, Chongqing, such as collapse of borehole wall and the existence of permeability loss of microfracture during drilling, and serious pollution of drilling environment with oil-based drilling fluid, a water-based drilling fluid system for anti-collapse and anti-leakage was studied. A water-based drilling fluid system with anti-collapse and anti-leakage was formed by introducing functional treatment agents, such as polypolysaccharide MEG, polymer emulsion film forming wall cementing agent LFGB, polyamine inhibitor LCFA and deformable particle plugging agent BXLZ, into the conventional water-based drilling fluid. After rolling at 130°C for 16 h, the system has good rheological properties, low filtration loss, good inhibition, lubrication and plugging properties. It has good plugging properties for 0.12 mm, 0.24 mm, 0.38 mm micro-cracks and 400 mD and 800 mD sand plates. The system was successfully tested on site in August 2019 in Fuling Reef Block, showing good rheological properties, solid wall plugging, and strong ability to seal and inhibit fracture expansion. There was no block falling in the drilling process, and the tripping, casing running and well cementing operations were all smooth, which provided a new technical idea and scheme for environmental protection and green drilling in Fuling shale gas exploitation.
基金the National Natural Science Foundation of China(Nos.22293031,22004083,21927806,82227801,and 82341023)the National Key R&D Program of China(No.2019YFA0905800)the Innovative research team of high-level local universities in Shanghai(No.SHSMU-ZLCX20212601)for their financial support.
文摘Cellular heterogeneity is a universal property of living systems,and the interrogation of single cells facilitates in-depth understanding of distinct cellular states and functions in various biological processes.Co-analysis of transcripts and proteins from the same single cells opens the way to decipher complex RNA regulatory frameworks and phenotypes,facilitating the understanding of cellular fate and function regulations,discovery of novel cell types,and construction of a high-resolution cell atlas.Herein,we review the state-of-art advances in the development of methodologies for co-analysis of single-cell transcripts and proteins.First,imaging-based methods are summarized with particular emphasis on optical and mass spectrometry imaging.Next,sequencing-based approaches for high-throughput and sensitive co-analysis of single-cell transcripts and proteins are described,including droplet-,microwell-,and split-pool-based platforms.Subsequently,combined methods with more flexibility and universality are discussed.These methods commonly employ different strategies or reactions to convert transcripts and proteins of single cells into distinct signals simultaneously,which can be detected by different instruments or platforms.Lastly,some perspectives on the future challenges and development trends in this field are presented.
基金the National Natural Science Foundation of China(No.61703413)the Science and Technology Innovation Program of Hunan Province,China(No.2021RC3078).
文摘This article provides a review on X-ray pulsar-based navigation(XNAV).The review starts with the basic concept of XNAV,and briefly introduces the past,present and future projects concerning XNAV.This paper focuses on the advances of the key techniques supporting XNAV,including the navigation pulsar database,the X-ray detection system,and the pulse time of arrival estimation.Moreover,the methods to improve the estimation performance of XNAV are reviewed.Finally,some remarks on the future development of XNAV are provided.
基金supported by the National Natural Science Foundation of China(No.32170121)the Fundamental Research Funds for the Central Universities(No.3132022159).
文摘3-Methylindole(skatole)is regarded as one of the most offensive compounds in odor emission.Biodegradation is feasible for skatole removal but the functional species and genes responsible for skatole degradation remain enigmatic.In this study,an efficient aerobic skatole-degrading consortium was obtained.Rhodococcus and Pseudomonas were identified as the two major and active populations by integrated metagenomic and metatranscriptomic analyses.Bioinformatic analyses indicated that the skatole downstream degradation wasmainly via the catechol pathway,and upstream degradation was likely catalyzed by the aromatic ring-hydroxylating oxygenase and flavin monooxygenase.Genome binning and gene analyses indicated that Pseudomonas,Pseudoclavibacter,and Raineyella should cooperate with Rhodococcus for the skatole degradation process.Moreover,a pure strain Rhodococcus sp.DMU1 was successfully obtained which could utilize skatole as the sole carbon source.Complete genome sequencing showed that strain DMU1 was the predominant population in the consortium.Further crude enzyme and RT-qPCR assays indicated that strain DMU1 degraded skatole through the catechol ortho-cleavage pathway.Collectively,our results suggested that synergistic degradation of skatole in the consortium should be performed by diverse bacteria with Rhodococcus as the primary degrader,and the degradation mainly proceeded via the catechol pathway.
基金Natural Science Foundation of China(Nos.82173585 and 82273741)Natural Science Foundation of Jiangsu Higher Education Institutions of China(Nos.21KJB330005 and 22KJB330007)+1 种基金Nanjing Important Science&Technology Specific Projects(No.2021-11005)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Background Socioeconomic status(SES)inequity was recognized as a driver of some certain infectious diseases.However,few studies evaluated the association between SES and the burden of overall infections,and even fewer identified preventable mediators.This study aimed to assess the association between SES and overall infectious diseases burden,and the potential roles of factors including lifestyle,environmental pollution,chronic disease history.Methods We included 401,009 participants from the UK Biobank(UKB)and defined the infection status for each participant according to their diagnosis records.Latent class analysis(LCA)was used to define SES for each participant.We further defined healthy lifestyle score,environment pollution score(EPS)and four types of chronic comorbidities.We used multivariate logistic regression to test the associations between the four above covariates and infectious diseases.Then,we performed the mediation and interaction analysis to explain the relationships between SES and other variables on infectious diseases.Finally,we employed seven types of sensitivity analyses,including considering the Townsend deprivation index as an area level SES variable,repeating our main analysis for some individual or composite factors and in some subgroups,as well as in an external data from the US National Health and Nutrition Examination Survey,to verify the main results.Results In UKB,60,771(15.2%)participants were diagnosed with infectious diseases during follow-up.Lower SES[odds ratio(OR)=1.5570]were associated with higher risk of overall infections.Lifestyle score mediated 2.9%of effects from SES,which ranged from 2.9 to 4.0%in different infection subtypes,while cardiovascular disease(CVD)mediated a proportion of 6.2%with a range from 2.1 to 6.8%.In addition,SES showed significant negative interaction with lifestyle score(OR=0.8650)and a history of cancer(OR=0.9096),while a significant synergy interaction was observed between SES and EPS(OR=1.0024).In subgroup analysis,we found that males and African(AFR)with lower SES showed much higher infection risk.Results from sensitivity and validation analyses showed relative consistent with the main analysis.Conclusions Low SES is shown to be an important risk factor for infectious disease,part of which may be mediated by poor lifestyle and chronic comorbidities.Efforts to enhance health education and improve the quality of living environment may help reduce burden of infectious disease,especially for people with low SES.
基金supported in part by the National Natural Science Foundation of China(No.41801313,41901397,and 61872388).
文摘Maritime transports play a critical role in international trade and commerce.Massive vessels sailing around the world continuously generate vessel trajectory data that contain rich spatial–temporal patterns of vessel navigations.Analyzing and understanding these patterns are valuable for maritime traffic surveillance and management.As essential techniques in complex data analysis and understanding,visualization and visual analysis have been widely used in vessel trajectory data analysis.This paper presents a literature review on the visualization and visual analysis of vessel trajectory data.First,we introduce commonly used vessel trajectory data sets and summarize main operations in vessel trajectory data preprocessing.Then,we provide a taxonomy of visualization and visual analysis of vessel trajectory data based on existing approaches and introduce representative works in details.Finally,we expound on the prospects of the remaining challenges and directions for future research.
基金National Natural Science Foundation of China(No.12105200,12175161,U186720)Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions+1 种基金Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),ChinaNuclear Energy Development Project,China(No.2016-1295).
文摘To estimate the physical dose of skin and key organs in a case of overexposure during a cardiac interventional procedure.Methods The female patient aged 50 suffered from owerexposure during ardiac interventional therapy in a hospital,Xinxiang city,Henan province,China in January 2020.The mesh-type phantom for the patient was constructed based on the adult mesh-type reference computational phantoms(MRCPs)released by the International Comission on Radiological Protection Publication 145 (ICRP145)and phantom deformation technology.Models of exposure scenario were constructed and simulated with particle and heavy ion transport code system(PHTTS)according to exposure conditions.Resuts:The maximum absorbed dose of key organs/tissues under iradiation in posteroanterior(PA)and 30°left anterior oblique directions(LOA)was 632.4 and 305.6 mGy,respectively.The let lung,heart,and left mammary gland received a larger dose under both iradiation conditions.The ratio of the absorbed dose with and without shielding was a lculated,and the relative difference in most organs was<1%between two directions.The iso-dose curve of the back skin revealed the ditribution of the absorbed dose(0.1-5.2 Gy).The dose estimate of key tssues/organs was higher than the conventional level,especially the local skin,up to 5.2 Gy.Concusions The interventional procedure in this ase resulted in a higher dose.Monte Carlo codes combined with the MRCPs can be employed to estimate physical dose to individuals in concrete irradia tion scenarios.
基金the National Natural Science Foundation of China(No.61703413).
文摘An accurate period is important to recover the pulse profile from a recorded photon event series of an X-ray pulsar and to estimate the pulse time of arrival,which is the measurement of X-ray pulsar navigation.Epoch folding is a classical period estimation method in the time domain;however,its computational complexity grows as the number of trail periods increases.In order to reduce the computational complexity,this paper improves the fast folding algorithm through segment correlation and amplitude accumulation,which is based on the post-order traversal of a binary tree.Compared with epoch folding,the improved fast folding algorithm can achieve a similar accuracy at the cost of a lower computational burden.Compared with the original fast folding algorithm,the improved algorithm can be applied to detectors with a much smaller effective area.The performance of the method is investigated by simulation data and observation data from the Neutron star Interior Composition Explorer(NICER).
