Chinese Beidou satellite navigation system constellation currently consists of eight Beidou satellites and can provide preliminary service of navigation and positioning in the Asia-Pacific Region.Based on the self-dev...Chinese Beidou satellite navigation system constellation currently consists of eight Beidou satellites and can provide preliminary service of navigation and positioning in the Asia-Pacific Region.Based on the self-developed software Position And Navigation Data Analysis(PANDA) and Beidou Experimental Tracking Stations (BETS),which are built by Wuhan University,the study of Beidou precise orbit determination,static precise point positioning (PPP),and high precision relative positioning,and differential positioning are carried out comprehensively.Results show that the radial precision of the Beidou satellite orbit determination is better than 10 centimeters.The RMS of static PPP can reach several centimeters to even millimeters for baseline relative positioning.The precision of kinematic pseudo-range differential positioning and RTK mode positioning are 2-4 m and 5-10 cm respectively,which are close to the level of GPS precise positioning.Research in this paper verifies that,with support of ground reference station network,Beidou satellite navigation system can provide precise positioning from several decimeters to meters in the wide area and several centimeters in the regional area.These promising results would be helpful for the implementation and applications of Beidou satellite navigation system.展开更多
BACKGROUND: Liver surgery has gone through the phases of wedge liver resection, regular resection of hepatic lobes, irregular and local resection, extracorporeal hepatectomy, hemi-extracorporeal hepatectomy and Da Vin...BACKGROUND: Liver surgery has gone through the phases of wedge liver resection, regular resection of hepatic lobes, irregular and local resection, extracorporeal hepatectomy, hemi-extracorporeal hepatectomy and Da Vinci surgical system-assisted hepatectomy. Taking advantage of modern technologies, liver surgery is stepping into an age of precise liver resection. This review aimed to analyze the comprehensive application of modern technologies in precise liver resection. DATA SOURCE: PubMed search was carried out for English-language articles relevant to precise liver resection, liver anatomy, hepatic blood inflow blockage, parenchyma transection, and down-staging treatment. RESULTS: The 3D image system can imitate the liver operation procedures, conduct risk assessment, help to identify the operation feasibility and confirm the operation scheme. In addition, some techniques including puncture and injection of methylene blue into the target Glisson sheath help to precisely determine the resection. Alternative methods such as Pringle maneuver are helpful for hepatic blood inflow blockage in precise liver resection. Moreover, the use of exquisite equipment for liver parenchyma transection, such as cavitron ultrasonic surgical aspirator, ultrasonic scalpel, Ligasure and Tissue Link is also helpful to reduce hemorrhage in liver resection, or even operate exsanguinous liver resection without blocking hepatic blood flow. Furthermore, various down-staging therapies including transcatheter arterial chemoembolization and radio-frequency ablation were appropriate for unresectable cancer, which reverse the advanced tumor back to early phase by local or systemic treatment so that hepatectomy or liver transplantation is possible.CONCLUSIONS: Modern technologies mentioned in this paper are the key tool for achieving precise liver resection and can effectively lead to maximum preservation of anatomical structural integrity and functions of the remnant liver. In addition, large randomized trials are needed to evaluate the usefuln展开更多
Genome editing is revolutionizing plant research and crop breeding.Sequence-specific nucleases(SSNs)such as zinc finger nuclease(ZFN)and TAL effector nuclease(TALEN)have been used to create site-specific DNA double-st...Genome editing is revolutionizing plant research and crop breeding.Sequence-specific nucleases(SSNs)such as zinc finger nuclease(ZFN)and TAL effector nuclease(TALEN)have been used to create site-specific DNA double-strand breaks and to achieve precise DNA modifications by promoting homology-directed repair(HDR)(Steinert et al.,2016;Voytas,2013).Later,RNA-guided SSNs such as CRISPR-Cas9,Cas12a,Cas12b,and their variants were applied for genome editing in plants(Li et al.,2013;Nekrasov et alM 2013;Tang et al.,2017;Zhong et al.,2019;Ming et al.,2020;Tang et al.,2019).However,HDR relies on simultaneous delivery of SSNs and DNA donors,which has been challenging in plants(Steinert et al.,2016;Zhang et aL,2019).Another challenge for realizing efficient HDR in plants is that DNA repair favors nonhomologous end joining(NHEJ)pathways over HDR in most cell types(Puchta,2005;Qi et al.,2013).展开更多
Supported atomically dispersed metal catalysts(ADMCs)have received enormous attention due to their high atom utilization efficiency,mass activity and excellent selectivity.Single-atom site catalysts(SACs)with monometa...Supported atomically dispersed metal catalysts(ADMCs)have received enormous attention due to their high atom utilization efficiency,mass activity and excellent selectivity.Single-atom site catalysts(SACs)with monometal-center as the quintessential ADMCs have been extensively studied in the catalysis-related fields.Beyond SACs,novel atomically dispersed metal catalysts(NADMCs)with flexible active sites featuring two or more catalytically centers including dual-atom and triple-atom catalysts have drawn ever-increasing attention recently.Owing to the presence of multiple neighboring active sites,NADMCs could exhibit much higher activity and selectivity compared with SACs,especially in those complicated reactions with multi-step intermediates.This review comprehensively outlines the recent exciting advances on the NADMCs with emphasis on the deeper understanding of the synergistic interactions among multiple metal atoms and underlying structure-performance relationships.It starts with the systematical introduction of principal synthetic approaches for NADMCs highlighting the key issues of each fabrication method including the atomically precise control in the design of metal nuclearity,and then the state-of-the-art characterizations for identifying and monitoring the atomic structure of NADMCs are explored.Thereafter,the recent development of NADMCs in energy-related applications is systematically discussed.Finally,we provide some new insights into the remaining challenges and opportunities for the development of NADMCs.展开更多
Spinal cord injury(SCI) leads to loss of motor and sensory function below the injury level and imposes a considerable burden on patients, families, and society. Repair of the injured spinal cord has been recognized as...Spinal cord injury(SCI) leads to loss of motor and sensory function below the injury level and imposes a considerable burden on patients, families, and society. Repair of the injured spinal cord has been recognized as a global medical challenge for many years.Significant progress has been made in research on the pathological mechanism of spinal cord injury. In particular, with the development of gene regulation, cell sequencing, and cell tracing technologies, in-depth explorations of the SCI microenvironment have become more feasible. However, translational studies related to repair of the injured spinal cord have not yielded significant results. This review summarizes the latest research progress on two aspects of SCI pathology: intraneuronal microenvironment imbalance and regenerative microenvironment imbalance. We also review repair strategies for the injured spinal cord based on microenvironment imbalance, including medications, cell transplantation, exosomes, tissue engineering, cell reprogramming, and rehabilitation. The current state of translational research on SCI and future directions are also discussed. The development of a combined, precise, and multitemporal strategy for repairing the injured spinal cord is a potential future direction.展开更多
Here we propose a method for extracting line-of-sight ionospheric observables from GPS data using precise point positioning(PPP).The PPP-derived ionospheric observables(PIOs) have identical form with their counterpart...Here we propose a method for extracting line-of-sight ionospheric observables from GPS data using precise point positioning(PPP).The PPP-derived ionospheric observables(PIOs) have identical form with their counterparts obtained from leveling the geometry-free GPS carrier-phase to code(leveling ionospheric observables,LIOs),and are affected by the satellite and receiver inter-frequency biases(IFBs).Based on the co-location experiments,the effects of extracting error arising from the observational noise and multipath on the PIOs and the LIOs are comparatively assessed,and the considerably reduced effects ranging from 70% to 75% on the PIOs with respect to the LIOs can be verified in our case.In addition,based on 26 consecutive days' GPS observations from two international GNSS service(IGS) sites(COCO,DAEJ) during disturbed ionosphere period,the extracted PIOs and LIOs are respectively used as the input of single-layer ionospheric model to retrieve daily satellite IFBs station-by-station.The minor extracting errors underlying the PIOs in contrast to the LIOs can also be proven by reducing day-to-day scatter and improving between-receiver consistency in the retrieved satellite IFBs values.展开更多
Optical logic operations lie at the heart of optical computing,and they enable many applications such as ultrahighspeed information processing.However,the reported optical logic gates rely heavily on the precise contr...Optical logic operations lie at the heart of optical computing,and they enable many applications such as ultrahighspeed information processing.However,the reported optical logic gates rely heavily on the precise control of input light signals,including their phase difference,polarization,and intensity and the size of the incident beams.Due to the complexity and difficulty in these precise controls,the two output optical logic states may suffer from an inherent instability and a low contrast ratio of intensity.Moreover,the miniaturization of optical logic gates becomes difficult if the extra bulky apparatus for these controls is considered.As such,it is desirable to get rid of these complicated controls and to achieve full logic functionality in a compact photonic system.Such a goal remains challenging.Here,we introduce a simple yet universal design strategy,capable of using plane waves as the incident signal,to perform optical logic operations via a diffractive neural network.Physically,the incident plane wave is first spatially encoded by a specific logic operation at the input layer and further decoded through the hidden layers,namely,a compound Huygens’metasurface.That is,the judiciously designed metasurface scatters the encoded light into one of two small designated areas at the output layer,which provides the information of output logic states.Importantly,after training of the diffractive neural network,all seven basic types of optical logic operations can be realized by the same metasurface.As a conceptual illustration,three logic operations(NOT,OR,and AND)are experimentally demonstrated at microwave frequencies.展开更多
In this paper, we obtain results on precise large deviations for non-random and random sums of negatively associated nonnegative random variables with common dominatedly varying tail distribution function. We discover...In this paper, we obtain results on precise large deviations for non-random and random sums of negatively associated nonnegative random variables with common dominatedly varying tail distribution function. We discover that, under certain conditions, three precise large-deviation prob- abilities with different centering numbers are equivalent to each other. Furthermore, we investigate precise large deviations for sums of negatively associated nonnegative random variables with certain negatively dependent occurrences. The obtained results extend and improve the corresponding results of Ng, Tang, Yan and Yang （J. Appl. Prob., 41, 93-107, 2004）.展开更多
In order to understand the crustal structure and tectonic background of the Changning–Gongxiang area, southeastern Sichuan Province, where a series of moderate-to-strong earthquakes occurred in recent years, we utili...In order to understand the crustal structure and tectonic background of the Changning–Gongxiang area, southeastern Sichuan Province, where a series of moderate-to-strong earthquakes occurred in recent years, we utilized the seismic phase data both from a local dense array and from the regional seismic networks;we used the tomoDD program to invert for the high-resolution three-dimensional velocity structure within the depth range of 0–10 km and for accurate hypocentral locations in this area. We analyzed the seismogenic structures for the events of Xingwen M5.7 in 2018 and Gongxian M5.3 and Changning M6.0 in 2019. The results show that:(1) widespread lateral inhomogeneity exists in the velocity structure of the study area, and the location of the velocity anomaly is largely consistent with known structures. In the range of distinguishable depth, the inhomogeneity decreases with increasing depth, and the velocity structure anomalies in some areas are continuous in depth;(2) earthquakes occurred in clusters, showing the characteristics of zonal folding trends in the NW-SE and NE-SW directions;the focal depth in the area is generally shallow in both the sedimentary cap and the crystalline basement. The seismogenic structures of small earthquake clusters are different in size and occurrence in different sections, and the clusters occurred mostly in regions with high P-or S-wave velocities;(3) synthesis of a variety of data suggests that the seismogenic structures of the Xingwen M5.7 and Changning M6.0 earthquakes are associated with slip faults that trend NW-SE in, respectively, the south wing and the axis of the Changning–Shuanghe anticline, while that of the Gongxian M5.3 earthquake is associated with thrust faults that trend N-S in the Jianwu syncline region. The dynamic sources of the three earthquakes are all from the SE pushing of the Qinghai–Tibet block on the Sichuan basin;(4) the risk of future strong earthquakes in this area must be reevaluated in light of the facts(a)that in recent years, moderate-t展开更多
Prime-editing systems have the capability to perform efficient and precise genome editing in human cells.In this study,we first developed a plant prime editor 2(pPE2)system and test its activity by generating a target...Prime-editing systems have the capability to perform efficient and precise genome editing in human cells.In this study,we first developed a plant prime editor 2(pPE2)system and test its activity by generating a targeted mutation on an HPT^(-ATG) reporter in rice.Our results showed that the pPE2 system could induce programmable editing at different genome sites.In transgenic T0 plants,pPE2-generated mutants occurred with 0%–31.3%frequency,suggesting that the efficiency of pPE2 varied greatly at different genomic sites and with prime-editing guide RNAs of diverse structures.To optimize editing efficiency,guide RNAs were introduced into the pPE2 system following the PE3 and PE3b strategy in human cells.However,at the genomic sites tested in this study,pPE3 systems generated only comparable or even lower editing frequencies.Furthemore,we developed a surrogate pPE2 system by incorporating the HPT^(-ATG) reporter to enrich the prime-edited cells.The nucleotide editing was easily detected in the resistant calli transformed with the surrogate pPE2 system,presumably due to the enhanced screening efficiency of edited cells.Taken together,our results indicate that plant prime-editing systems we developed could provide versatile and flexible editing in rice genome.展开更多
In the present paper, some precise fundamental inequalities are introduced. Applying them,we obtain the precise estimate for the sum of deficiencies. Let f(z) be transcendental mero-morphic in the finite plane and k b...In the present paper, some precise fundamental inequalities are introduced. Applying them,we obtain the precise estimate for the sum of deficiencies. Let f(z) be transcendental mero-morphic in the finite plane and k be a positive integer. If ε is an arbitrary positive numberand a and b are two distinct finite complex numbers, then we have T(r,f)<(1+1/k)N (r,1/f)+(1+1/k)N (r,1/(f^(k)-1)) -N (r,1/(f(k+1))+εT(r,f)+S(r,f)and δ(a,f^(k))+δ(b,f^(k))≤1+1/(2k+1).展开更多
The authors achieve a general law of precise asymptotics for a new kind of complete moment convergence of i.i.d. random variables, which includes complete con- vergence as a special case. It can describe the relations...The authors achieve a general law of precise asymptotics for a new kind of complete moment convergence of i.i.d. random variables, which includes complete con- vergence as a special case. It can describe the relations among the boundary function, weighted function, convergence rate and limit value in studies of complete convergence. This extends and generalizes the corresponding results of Liu and Lin in 2006.展开更多
Fish biology has been developed for more than 100 years,but some important breakthroughs have been made in the last decade.Early studies commonly concentrated on morphology,phylogenetics,development,growth,reproductio...Fish biology has been developed for more than 100 years,but some important breakthroughs have been made in the last decade.Early studies commonly concentrated on morphology,phylogenetics,development,growth,reproduction manipulation,and disease control.Recent studies have mostly focused on genetics,molecular biology,genomics,and genome biotechnologies,which have provided a solid foundation for enhancing aquaculture to ensure food security and improving aquatic environments to sustain ecosystem health.Here,we review research advances in five major areas:(1)biological innovations and genomic evolution of four significant fish lineages including non-teleost ray-finned fishes,northern hemisphere sticklebacks,East African cichlid fishes,and East Asian cyprinid fishes;(2)evolutionary fates and consequences of natural polyploid fishes;(3)biological consequences of fish domestication and selection;(4)development and innovation of fish breeding biotechnologies;and(5)applicable approaches and potential of fish genetic breeding biotechnologies.Moreover,five precision breeding biotechniques are examined and discussed in detail including gene editing for the introgression or removal of beneficial or detrimental alleles,use of sex-specific markers for the production of mono-sex populations,controllable primordial germ cell on-off strategy for producing sterile offspring,surrogate broodstock-based strategies to accelerate breeding,and genome incorporation and sexual reproduction regainbased approach to create synthetic polyploids.Based on these scientific and technological advances,we propose a blueprint for genetic improvement and new breed creation for aquaculture species and analyze the potential of these new breeding strategies for improving aquaculture seed industry and strengthening food security.展开更多
For the widely orthant dependent （WOD） structure, this paper mainly investigates the precise large deviations for the partial sums of WOD and non-identically distributed random variables with dominatedly varying tai...For the widely orthant dependent （WOD） structure, this paper mainly investigates the precise large deviations for the partial sums of WOD and non-identically distributed random variables with dominatedly varying tails. The obtained results extend some corresponding results.展开更多
文摘Chinese Beidou satellite navigation system constellation currently consists of eight Beidou satellites and can provide preliminary service of navigation and positioning in the Asia-Pacific Region.Based on the self-developed software Position And Navigation Data Analysis(PANDA) and Beidou Experimental Tracking Stations (BETS),which are built by Wuhan University,the study of Beidou precise orbit determination,static precise point positioning (PPP),and high precision relative positioning,and differential positioning are carried out comprehensively.Results show that the radial precision of the Beidou satellite orbit determination is better than 10 centimeters.The RMS of static PPP can reach several centimeters to even millimeters for baseline relative positioning.The precision of kinematic pseudo-range differential positioning and RTK mode positioning are 2-4 m and 5-10 cm respectively,which are close to the level of GPS precise positioning.Research in this paper verifies that,with support of ground reference station network,Beidou satellite navigation system can provide precise positioning from several decimeters to meters in the wide area and several centimeters in the regional area.These promising results would be helpful for the implementation and applications of Beidou satellite navigation system.
基金supported by grants from the National Natural Science Foundation of China (81172095, 81171135 and 81200324)Bureau of Health Medical Scientific Research Foundation of Hainan Province (Qiongwei 2012 PT-70)China Postdoctoral Science Foundation funded project (2012m521875)
文摘BACKGROUND: Liver surgery has gone through the phases of wedge liver resection, regular resection of hepatic lobes, irregular and local resection, extracorporeal hepatectomy, hemi-extracorporeal hepatectomy and Da Vinci surgical system-assisted hepatectomy. Taking advantage of modern technologies, liver surgery is stepping into an age of precise liver resection. This review aimed to analyze the comprehensive application of modern technologies in precise liver resection. DATA SOURCE: PubMed search was carried out for English-language articles relevant to precise liver resection, liver anatomy, hepatic blood inflow blockage, parenchyma transection, and down-staging treatment. RESULTS: The 3D image system can imitate the liver operation procedures, conduct risk assessment, help to identify the operation feasibility and confirm the operation scheme. In addition, some techniques including puncture and injection of methylene blue into the target Glisson sheath help to precisely determine the resection. Alternative methods such as Pringle maneuver are helpful for hepatic blood inflow blockage in precise liver resection. Moreover, the use of exquisite equipment for liver parenchyma transection, such as cavitron ultrasonic surgical aspirator, ultrasonic scalpel, Ligasure and Tissue Link is also helpful to reduce hemorrhage in liver resection, or even operate exsanguinous liver resection without blocking hepatic blood flow. Furthermore, various down-staging therapies including transcatheter arterial chemoembolization and radio-frequency ablation were appropriate for unresectable cancer, which reverse the advanced tumor back to early phase by local or systemic treatment so that hepatectomy or liver transplantation is possible.CONCLUSIONS: Modern technologies mentioned in this paper are the key tool for achieving precise liver resection and can effectively lead to maximum preservation of anatomical structural integrity and functions of the remnant liver. In addition, large randomized trials are needed to evaluate the usefuln
文摘Genome editing is revolutionizing plant research and crop breeding.Sequence-specific nucleases(SSNs)such as zinc finger nuclease(ZFN)and TAL effector nuclease(TALEN)have been used to create site-specific DNA double-strand breaks and to achieve precise DNA modifications by promoting homology-directed repair(HDR)(Steinert et al.,2016;Voytas,2013).Later,RNA-guided SSNs such as CRISPR-Cas9,Cas12a,Cas12b,and their variants were applied for genome editing in plants(Li et al.,2013;Nekrasov et alM 2013;Tang et al.,2017;Zhong et al.,2019;Ming et al.,2020;Tang et al.,2019).However,HDR relies on simultaneous delivery of SSNs and DNA donors,which has been challenging in plants(Steinert et al.,2016;Zhang et aL,2019).Another challenge for realizing efficient HDR in plants is that DNA repair favors nonhomologous end joining(NHEJ)pathways over HDR in most cell types(Puchta,2005;Qi et al.,2013).
基金the Beijing Natural Science Foundation(No.2224096)the National Key R&D Program of China(No.2018YFA0702003)+3 种基金the Science and Technology Key Project of Guangdong Province,China(No.2020B010188002)the China Postdoctoral Science Foundation(Nos.2021M690086 and 2021TQ0170)X.B.Z.acknowledges funding support from the Office of China Postdoctoral Council(No.YJ20200277)the“Shuimu Tsinghua Scholar Program"(No.2020SM109)of Tsinghua University,China.
文摘Supported atomically dispersed metal catalysts(ADMCs)have received enormous attention due to their high atom utilization efficiency,mass activity and excellent selectivity.Single-atom site catalysts(SACs)with monometal-center as the quintessential ADMCs have been extensively studied in the catalysis-related fields.Beyond SACs,novel atomically dispersed metal catalysts(NADMCs)with flexible active sites featuring two or more catalytically centers including dual-atom and triple-atom catalysts have drawn ever-increasing attention recently.Owing to the presence of multiple neighboring active sites,NADMCs could exhibit much higher activity and selectivity compared with SACs,especially in those complicated reactions with multi-step intermediates.This review comprehensively outlines the recent exciting advances on the NADMCs with emphasis on the deeper understanding of the synergistic interactions among multiple metal atoms and underlying structure-performance relationships.It starts with the systematical introduction of principal synthetic approaches for NADMCs highlighting the key issues of each fabrication method including the atomically precise control in the design of metal nuclearity,and then the state-of-the-art characterizations for identifying and monitoring the atomic structure of NADMCs are explored.Thereafter,the recent development of NADMCs in energy-related applications is systematically discussed.Finally,we provide some new insights into the remaining challenges and opportunities for the development of NADMCs.
基金the National Key Research and Development Project of Stem Cell and Transformation Research(2019YFA0112100).
文摘Spinal cord injury(SCI) leads to loss of motor and sensory function below the injury level and imposes a considerable burden on patients, families, and society. Repair of the injured spinal cord has been recognized as a global medical challenge for many years.Significant progress has been made in research on the pathological mechanism of spinal cord injury. In particular, with the development of gene regulation, cell sequencing, and cell tracing technologies, in-depth explorations of the SCI microenvironment have become more feasible. However, translational studies related to repair of the injured spinal cord have not yielded significant results. This review summarizes the latest research progress on two aspects of SCI pathology: intraneuronal microenvironment imbalance and regenerative microenvironment imbalance. We also review repair strategies for the injured spinal cord based on microenvironment imbalance, including medications, cell transplantation, exosomes, tissue engineering, cell reprogramming, and rehabilitation. The current state of translational research on SCI and future directions are also discussed. The development of a combined, precise, and multitemporal strategy for repairing the injured spinal cord is a potential future direction.
基金supported by National Basic Research Program of China(Grant No. 2012CB82560X)National Natural Science Foundation of China (Grant Nos. 41174015 and 41074013)
文摘Here we propose a method for extracting line-of-sight ionospheric observables from GPS data using precise point positioning(PPP).The PPP-derived ionospheric observables(PIOs) have identical form with their counterparts obtained from leveling the geometry-free GPS carrier-phase to code(leveling ionospheric observables,LIOs),and are affected by the satellite and receiver inter-frequency biases(IFBs).Based on the co-location experiments,the effects of extracting error arising from the observational noise and multipath on the PIOs and the LIOs are comparatively assessed,and the considerably reduced effects ranging from 70% to 75% on the PIOs with respect to the LIOs can be verified in our case.In addition,based on 26 consecutive days' GPS observations from two international GNSS service(IGS) sites(COCO,DAEJ) during disturbed ionosphere period,the extracted PIOs and LIOs are respectively used as the input of single-layer ionospheric model to retrieve daily satellite IFBs station-by-station.The minor extracting errors underlying the PIOs in contrast to the LIOs can also be proven by reducing day-to-day scatter and improving between-receiver consistency in the retrieved satellite IFBs values.
基金sponsored by the National Natural Science Foundation of China(NNSFC)under Grants Nos.61625502,11961141010,and 61975176the Top-Notch Young Talents Programme of China+4 种基金the Fundamental Research Funds for the Central UniversitiesNanyang Technological University for NAP Start-Up Grantthe Singapore Ministry of Education(Grant Nos.MOE2018-T2-1-022(S),MOE2016-T3-1-006 and Tier 1 RG174/16(S))supported by the Chinese Scholarship Council(CSC No.201906320294)Zhejiang University Academic Award for Outstanding Doctoral Candidates.
文摘Optical logic operations lie at the heart of optical computing,and they enable many applications such as ultrahighspeed information processing.However,the reported optical logic gates rely heavily on the precise control of input light signals,including their phase difference,polarization,and intensity and the size of the incident beams.Due to the complexity and difficulty in these precise controls,the two output optical logic states may suffer from an inherent instability and a low contrast ratio of intensity.Moreover,the miniaturization of optical logic gates becomes difficult if the extra bulky apparatus for these controls is considered.As such,it is desirable to get rid of these complicated controls and to achieve full logic functionality in a compact photonic system.Such a goal remains challenging.Here,we introduce a simple yet universal design strategy,capable of using plane waves as the incident signal,to perform optical logic operations via a diffractive neural network.Physically,the incident plane wave is first spatially encoded by a specific logic operation at the input layer and further decoded through the hidden layers,namely,a compound Huygens’metasurface.That is,the judiciously designed metasurface scatters the encoded light into one of two small designated areas at the output layer,which provides the information of output logic states.Importantly,after training of the diffractive neural network,all seven basic types of optical logic operations can be realized by the same metasurface.As a conceptual illustration,three logic operations(NOT,OR,and AND)are experimentally demonstrated at microwave frequencies.
基金Research supported by National Science Foundation of China(No.10271087)
文摘In this paper, we obtain results on precise large deviations for non-random and random sums of negatively associated nonnegative random variables with common dominatedly varying tail distribution function. We discover that, under certain conditions, three precise large-deviation prob- abilities with different centering numbers are equivalent to each other. Furthermore, we investigate precise large deviations for sums of negatively associated nonnegative random variables with certain negatively dependent occurrences. The obtained results extend and improve the corresponding results of Ng, Tang, Yan and Yang （J. Appl. Prob., 41, 93-107, 2004）.
基金supported by National Natural Science Foundation of China (No. 41574047)Sichuan–Yunnan national earthquake monitoring and prediction experimental field project (2016CESE0101, 2018CSES0209)Project of Science for Earthquake Resilience (XH202302)
文摘In order to understand the crustal structure and tectonic background of the Changning–Gongxiang area, southeastern Sichuan Province, where a series of moderate-to-strong earthquakes occurred in recent years, we utilized the seismic phase data both from a local dense array and from the regional seismic networks;we used the tomoDD program to invert for the high-resolution three-dimensional velocity structure within the depth range of 0–10 km and for accurate hypocentral locations in this area. We analyzed the seismogenic structures for the events of Xingwen M5.7 in 2018 and Gongxian M5.3 and Changning M6.0 in 2019. The results show that:(1) widespread lateral inhomogeneity exists in the velocity structure of the study area, and the location of the velocity anomaly is largely consistent with known structures. In the range of distinguishable depth, the inhomogeneity decreases with increasing depth, and the velocity structure anomalies in some areas are continuous in depth;(2) earthquakes occurred in clusters, showing the characteristics of zonal folding trends in the NW-SE and NE-SW directions;the focal depth in the area is generally shallow in both the sedimentary cap and the crystalline basement. The seismogenic structures of small earthquake clusters are different in size and occurrence in different sections, and the clusters occurred mostly in regions with high P-or S-wave velocities;(3) synthesis of a variety of data suggests that the seismogenic structures of the Xingwen M5.7 and Changning M6.0 earthquakes are associated with slip faults that trend NW-SE in, respectively, the south wing and the axis of the Changning–Shuanghe anticline, while that of the Gongxian M5.3 earthquake is associated with thrust faults that trend N-S in the Jianwu syncline region. The dynamic sources of the three earthquakes are all from the SE pushing of the Qinghai–Tibet block on the Sichuan basin;(4) the risk of future strong earthquakes in this area must be reevaluated in light of the facts(a)that in recent years, moderate-t
基金funded by the Genetically Modified Breeding Major Projects(no.2019ZX08010003-001-008 and no.2016ZX08010-002-008)the National Natural Science Foundation of China(no.U19A2022).
文摘Prime-editing systems have the capability to perform efficient and precise genome editing in human cells.In this study,we first developed a plant prime editor 2(pPE2)system and test its activity by generating a targeted mutation on an HPT^(-ATG) reporter in rice.Our results showed that the pPE2 system could induce programmable editing at different genome sites.In transgenic T0 plants,pPE2-generated mutants occurred with 0%–31.3%frequency,suggesting that the efficiency of pPE2 varied greatly at different genomic sites and with prime-editing guide RNAs of diverse structures.To optimize editing efficiency,guide RNAs were introduced into the pPE2 system following the PE3 and PE3b strategy in human cells.However,at the genomic sites tested in this study,pPE3 systems generated only comparable or even lower editing frequencies.Furthemore,we developed a surrogate pPE2 system by incorporating the HPT^(-ATG) reporter to enrich the prime-edited cells.The nucleotide editing was easily detected in the resistant calli transformed with the surrogate pPE2 system,presumably due to the enhanced screening efficiency of edited cells.Taken together,our results indicate that plant prime-editing systems we developed could provide versatile and flexible editing in rice genome.
基金Project partially supported by the National Natural Science Foundation of China.
文摘In the present paper, some precise fundamental inequalities are introduced. Applying them,we obtain the precise estimate for the sum of deficiencies. Let f(z) be transcendental mero-morphic in the finite plane and k be a positive integer. If ε is an arbitrary positive numberand a and b are two distinct finite complex numbers, then we have T(r,f)<(1+1/k)N (r,1/f)+(1+1/k)N (r,1/(f^(k)-1)) -N (r,1/(f(k+1))+εT(r,f)+S(r,f)and δ(a,f^(k))+δ(b,f^(k))≤1+1/(2k+1).
基金supported by the National Natural Science Foundation of China(No.10571073)the 985 Program of Jilin University.
文摘The authors achieve a general law of precise asymptotics for a new kind of complete moment convergence of i.i.d. random variables, which includes complete con- vergence as a special case. It can describe the relations among the boundary function, weighted function, convergence rate and limit value in studies of complete convergence. This extends and generalizes the corresponding results of Liu and Lin in 2006.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDB31000000)the Consulting Research Projects of Hubei Institute of Chinese Engineering Development Strategies and Academic Divisions of the Chinese Academy of Sciences(2021-SM02-B-010)+2 种基金the Key Program of Frontier Sciences of the Chinese Academy of Sciences(Grant No.QYZDY-SSW-SMC025)the China Agriculture Research System(CARS-45-07)the Autonomous Project of the State Key Laboratory of Freshwater Ecology and Biotechnology(2019FBZ04).
文摘Fish biology has been developed for more than 100 years,but some important breakthroughs have been made in the last decade.Early studies commonly concentrated on morphology,phylogenetics,development,growth,reproduction manipulation,and disease control.Recent studies have mostly focused on genetics,molecular biology,genomics,and genome biotechnologies,which have provided a solid foundation for enhancing aquaculture to ensure food security and improving aquatic environments to sustain ecosystem health.Here,we review research advances in five major areas:(1)biological innovations and genomic evolution of four significant fish lineages including non-teleost ray-finned fishes,northern hemisphere sticklebacks,East African cichlid fishes,and East Asian cyprinid fishes;(2)evolutionary fates and consequences of natural polyploid fishes;(3)biological consequences of fish domestication and selection;(4)development and innovation of fish breeding biotechnologies;and(5)applicable approaches and potential of fish genetic breeding biotechnologies.Moreover,five precision breeding biotechniques are examined and discussed in detail including gene editing for the introgression or removal of beneficial or detrimental alleles,use of sex-specific markers for the production of mono-sex populations,controllable primordial germ cell on-off strategy for producing sterile offspring,surrogate broodstock-based strategies to accelerate breeding,and genome incorporation and sexual reproduction regainbased approach to create synthetic polyploids.Based on these scientific and technological advances,we propose a blueprint for genetic improvement and new breed creation for aquaculture species and analyze the potential of these new breeding strategies for improving aquaculture seed industry and strengthening food security.
文摘For the widely orthant dependent （WOD） structure, this paper mainly investigates the precise large deviations for the partial sums of WOD and non-identically distributed random variables with dominatedly varying tails. The obtained results extend some corresponding results.
