Two-axis transportable satellite antennas(TATSAs) have been widely adopted owing to its simple structure and low cost. However, by searching in a wide range, it will take a very long searching time. Under extreme cond...Two-axis transportable satellite antennas(TATSAs) have been widely adopted owing to its simple structure and low cost. However, by searching in a wide range, it will take a very long searching time. Under extreme conditions, it will even fail to work. In this paper, we propose a novel roll compensation(RC) method for the low-cost TATSAs to achieve faster tracking even if when the antenna has no azimuth sensor. By analyzing the influence of roll axis on the system performance, details of the compensation method are derived. Simulation and measurement results indicate that the proposed RC method can effectively reduce the initial searching time for satellite communication. In addition, tracking along with the ellipse path with the RC method provides the highest tracking efficiency.展开更多
We present two cavity-stabilized lasers at 1555 nm, which are built to be the frequency source for a transportable photonic microwave generation system. The frequency instability reaches the thermal noise limit （7 &#...We present two cavity-stabilized lasers at 1555 nm, which are built to be the frequency source for a transportable photonic microwave generation system. The frequency instability reaches the thermal noise limit （7 ×10-16） of the 10-cm ultra-low expansion glass cavity at 1-10s averaging time and the beat signal of the two lasers reveals a remarkable linewidth of 185mHz.展开更多
We report an experimental demonstration of geopotential difference measurement using a pair of transportable ^(40)Ca^(+) optical clocks(TOC-729-1 and TOC-729-3)in the laboratory,each of them has an uncertainty of 1.3&...We report an experimental demonstration of geopotential difference measurement using a pair of transportable ^(40)Ca^(+) optical clocks(TOC-729-1 and TOC-729-3)in the laboratory,each of them has an uncertainty of 1.3×10^(−17) and an instability of 4.8×10^(−15)/√τ.Referenced to a stationary clock of TOC-729-1,the geopotential difference measurements are realized by moving TOC-729-3 to three different locations and the relevant altitude differences are measured with uncertainties at the level of 20 cm.After correcting the systematic shifts(including gravitational red shift),the two-clock frequency difference is measured to be–0.7(2.2)×10^(−17),considering both the statistic(1.0×10^(−17))and the systematic(1.9×10^(−17))uncertainties.The frequency difference between these two clocks is within their respective uncertainties,verifying the reliability of transportable ^(40)Ca^(+) optical clocks at the low level of 10^(−17).展开更多
This paper studies single-parent family conversation mainly,the researcher takes 10 hours of recordings in a single-parent family in Shenzhen as data to study conversational identity construction.
This paper proposes a new method for service restoration of distribution network with the support of transportable power sources(TPSs)and repair crews(RCs).Firstly,a coupling model of distribution networks and vehicle...This paper proposes a new method for service restoration of distribution network with the support of transportable power sources(TPSs)and repair crews(RCs).Firstly,a coupling model of distribution networks and vehicle routing of TPSs and RCs is proposed,where the TPSs serve as emergency power supply sources,and the RCs are used to repair the faulted lines.Considering the uncertainty of traffic congestion,the probability distribution of the travel time spent on each road is derived based on the Nesterov user equilibrium model,and a two-stage stochastic program is formulated to determine the optimal routings of TPSs and RCs.To efficiently solve the proposed stochastic mixed-integer linear program(MILP),a two-phase scenario reduction method is then developed to scale down the problem size,and an adaptive progressive hedging algorithm is used for an efficient solution.The effectiveness of the proposed methods and algorithms has been illustrated in a modified IEEE 33-bus system.展开更多
A high-performance transportable fountain clockis attractive for use in laboratories with high-precisiontime-frequency measurement requirements. This Letterreports the improvement of the stability of atransportable ru...A high-performance transportable fountain clockis attractive for use in laboratories with high-precisiontime-frequency measurement requirements. This Letterreports the improvement of the stability of atransportable rubidium-87 fountain clock because of anoptimization of temperature characteristics. This clockintegrates its physical packaging, optical benches,microwave frequency synthesizers, and electronic controlsonto an easily movable wheeled plate. Two optical bencheswith a high-vibration resistance are realized in thiswork. No additional adjustment is required after movingthem several times. The Allan deviation of the fountainclock frequency was measured by comparing it with that ofthe hydrogen maser. The fountain clock got a short-termstability of 2.3×10^-13 at 1 s and long-term stabilityon the order of 10-16 at 100,000 s.展开更多
Microrobots play an essential role in early diagnosis and precision medicine with the increasing demands for controllability in bio-medicine and micromanipulation,which can complete the pre-designed behavior under ext...Microrobots play an essential role in early diagnosis and precision medicine with the increasing demands for controllability in bio-medicine and micromanipulation,which can complete the pre-designed behavior under external stimulation.However,most microrobots are currently made of a single material system and focus on fabricating a driving module as the main structure of microrobots.This hinders the integration of diverse functions in one microrobot to fulfill the complex application.Here,a multi-material and multi-module hand-microrobot based on femtosecond laser direct writing technology is proposed,which has a pH-responsive capturing module and a magnetic-responsive transportation module(MRTM).This microrobot can not only respond to pH for capturing and releasing objects,but also respond to magnetic fields for cargo delivery even with obstacles.The two responding modules of the hand-microrobot are fabricated independently,and can collaborate with each other to achieve the delivery of target objects like polystyrene(PS)microsphere(10µm)or 786-O cell by capturing,transporting,and spatial rolling.Besides,the MRTM can be locally fabricated on any prefabricated static structure,so that the whole microrobot can achieve controllable motion.This strategy is expected to be used to manipulate cells,deliver drugs for precise treatment,and environmental treatment.展开更多
Noncohesive particle clusters are identified and tracked in turbulent flows to determine the breakdown and time evolution of cluster statistics and their implications for interscale mass transfer,which has connections...Noncohesive particle clusters are identified and tracked in turbulent flows to determine the breakdown and time evolution of cluster statistics and their implications for interscale mass transfer,which has connections to the classical turbulent energy cascade and its mass cascade counterpart running in parallel.In particular,the formation and dynamics of sediment and larvae clusters are of interest to coral larvae settlement in coastal regions and particularly the resilience of green-gray coastal protection solutions.Analogous cluster behavior is relevant to cloud microphysics and precipitation initiation,radiation transport and light transmission through colloids and suspensions,heat and mass transfer in particle-laden flows,and viral and pollutant transmission.Following a comparison between various clustering techniques,we adopt a density-based cluster identification algorithm based on its simplicity and efficiency,where particles are clustered based on the number of neighboring particles in their individual spheres of influence.We establish parallels with lattice-based percolation theory,as evident in the power-law scaling of the cluster size distribution near the percolation threshold.The degree of discontinuity of the phase transition associated with this percolation threshold is observed to broaden with larger Stokes numbers and thereby large-scale clustering.The sensitivity of our findings to the employed clustering algorithm is discussed.A novel cluster tracking algorithm is deployed to determine the interscale transfer rate along the particle-number phase-space dimension via accounting of cluster breakup and merger events,extending previous work on the bubble breakup cascade beneath surface breaking waves.Our findings shed light on the interaction between particle clusters and their carrier turbulent flows,with an eye toward transport models incorporating cluster characteristics and dynamics.展开更多
The longitudinal π-extension of carbon nanohoops is one of the most effective bottom-up synthetic strategies toward carbon nanotubes(CNTs).Herein,the precise synthesis of a multi-substituted carbon nanohoop([12]CPP-8...The longitudinal π-extension of carbon nanohoops is one of the most effective bottom-up synthetic strategies toward carbon nanotubes(CNTs).Herein,the precise synthesis of a multi-substituted carbon nanohoop([12]CPP-8PBPy)based on cycloparaphenylenes(CPPs)grafted with eight pyrene-functionalized units was reported.This structurally well-defined nanohoop not only acts as a segment of armchair-type CNTs but also achieves enhanced longitudinal π-extension.The structure of[12]CPP-8PBPy was confirmed by high-resolution mass spectrometry(HRMS)and nuclear magnetic resonance(NMR).The photophysical properties were studied by UV/Vis and photoluminescence spectroscopy.The potential applications of[12]CPP-8PBPy in electron-transport devices were further investigated.展开更多
Post-quantum transport layer security(PQ-TLS)is capable of effectively defending against quantum threats to current network communications,whereas its larger public key and certificate sizes as well as higher computat...Post-quantum transport layer security(PQ-TLS)is capable of effectively defending against quantum threats to current network communications,whereas its larger public key and certificate sizes as well as higher computational overhead may result in a significant performance reduction compared with conventional TLS.In this paper,we present a systematic evaluation of PQ-TLS performance across diverse deployment scenarios to address the following critical research questions.(1)What is the performance behavior of PQ-TLS across different TLS modes?(2)How does PQ-TLS perform across varying client scales?(3)Which network topology is most suitable for PQ-TLS?(4)How does PQ-TLS perform on personal computers(PCs)compared to embedded IoT devices?To the best of our knowledge,this is the first work to comprehensively address these issues,offering implementers some insights into PQ-TLS performance and guidance for optimizing it across diverse scenarios.展开更多
This research conducts a comprehensive experimental study of the entire filling system process at the Weishan Lake Rare Earth Mine(WSLREM)in Shandong Province,encompassing tailings thickening,feeding,slurry preparatio...This research conducts a comprehensive experimental study of the entire filling system process at the Weishan Lake Rare Earth Mine(WSLREM)in Shandong Province,encompassing tailings thickening,feeding,slurry preparation,and pipeline transportation.It proposes a complete and efficient upgrade solution for an intelligent paste filling system.The results show that the F1 flocculant was selected to prepare a flocculant solution with a solution concentration of 0.1%.The unit consumption is set to 25 g·t^(-1),and the flocculation and sedimentation effects are optimal when the mass concentration is 15%,with an underflow concentration of 62%.The selection experiment of cementitious material shows that the effect of using new cementitious material is better than that of traditional 32.5R Portland cement.At the same time,rheological experiments on the filling slurry were carried out,and the filling transportation pressure was studied by combining theoretical calculations with numerical simulations.The research results have guiding significance for the debugging of filling pumps and the selection of a filling pipeline.After the application of industrial transformation,the underflow concentration of the sand silo was 64%–66%,the slurry concentration was 68%–72%,the addition range of the cementing material was 1∶16–1∶4,and the filling capacity was 40–60 m^(3)·h^(-1).The intelligent upgrade and transformation of the filling system have yielded remarkable results,providing significant reference value for the intelligent filling transformation of similar mines.展开更多
Purpose-This paper provides a comprehensive analysis of the Brazilian freight railway system,examining the efficacy of the current concession renewal model in light of persistent structural problems such as market con...Purpose-This paper provides a comprehensive analysis of the Brazilian freight railway system,examining the efficacy of the current concession renewal model in light of persistent structural problems such as market concentration,cargo dependence on export commodities and underutilization of the network.Situating Brazil within the broader international debate on railway reforms,the paper evaluates whether the ongoing early renewal of concessions can deliver a more diversified and competitive freight system.Design/methodology/approach-The study adopts a sequential mixed-methods research design that integrates longitudinal quantitative analysis with qualitative institutional and policy evaluation.The quantitative component examines time-series indicators published by ANTT,DNIT and INFRA S.A.from 1999 to 2023 to identify structural patterns in traffic growth,investment,safety and market concentration.The qualitative component employs a process-tracing logic to reconstruct the evolution of concession renewals and the implementation of Railway Law 14.273/2021,drawing on concepts from regulatory economics,institutional theory and industrial organization.These empirical streams are synthesized through an analytical framework that connects three dimensions-regulatory design,market structure and system performance-allowing for a systematic assessment of how Brazil’s institutional configuration shapes incentives,competitive dynamics and network utilization.Findings-The analysis confirms that the early renewal of concessions has successfully secured substantial private investment for capacity expansion on existing trunk lines.However,it has perpetuated the vertically integrated model,reinforcing the market power of incumbent operators and failing to significantly promote intramodal competition or cargo diversification.The system remains dominated by iron ore and agricultural commodities,with general cargo representing a minuscule share.The new authorization regime and short-line railway policies present a viable pathway for market opening but face significant operational and institutional barriers to implementation.Originality/value-This research offers a timely and critical assessment of a pivotal moment in Brazilian railway policy.It moves beyond a simplistic evaluation of volume growth to a structural analysis of market failures and the interplay between concession renewal and regulatory innovation.The findings provide actionable insights for policymakers in Brazil and other emerging economies seeking to balance private investment with public interest goals in railway infrastructure,highlighting the necessity of complementary,pro-competitive measures alongside financial investment.展开更多
Synergistically improving the yield and grain quality of rice remains a major breeding challenge.Amino acid transporters play key roles in regulating plant growth and development,but their mechanisms in synergisticall...Synergistically improving the yield and grain quality of rice remains a major breeding challenge.Amino acid transporters play key roles in regulating plant growth and development,but their mechanisms in synergistically regulating yield and quality remain unclear.Here,we report that the plasma membrane-localized transporter OsAAP18,which is more highly expressed in indica than japonica rice,positively correlates with tiller number and yield but negatively with grain width.OsAAP18 transports eight amino acids,including asparagine(Asn),proline(Pro),leucine(Leu),and valine(Val).Its overexpression increases yield through enhanced tillering and grain number per panicle while also improving rice processing and cooking quality.Transcriptome analysis showed that OsAAP18 coordinates grain development and quality formation by regulating the expression of key genes involved in starch and sucrose metabolism,nitrogen metabolism,and plant hormone signaling pathways.These findings establish OsAAP18 as a dual-function regulator that synergistically enhances yield and quality,offering a promising target for rice breeding.展开更多
Aging is characterized by a decreased autophagic activity contributing to the intracellular deposition of damaged organelles and macromolecules.Autophagy is particularly challenging in neurons since autophagic vesicle...Aging is characterized by a decreased autophagic activity contributing to the intracellular deposition of damaged organelles and macromolecules.Autophagy is particularly challenging in neurons since autophagic vesicles are formed at the axonal tip and must be transported to the soma where final degradation occurs.Here,we examined if axonal transport of autophagic vesicles is altered during aging.We employed two-photon microscopy for in vivo imaging in the optic nerve of young and aged rats.In old animals(>18 months old),retrograde autophagic vesicle transport was significantly reduced with regard to motility and velocity.While activation of autophagy was decreased,expression of key proteins of the autophagy-lysosomal pathway including p62 and procathepsin D and the number of autophagolysosomes was increased.Maturation of autophagic vesicles was shifted to more distal regions of the axon and axonal lysosomal clearing was impaired.In a pull-down assay,the protein binding between dynein and dynactin was decreased by half,which could explain the retrograde axonal transport effects.Taken together,retrograde axonal autophagic vesicle transport in vivo is diminished during aging accompanied by decreased autophagy activation,alterations of the lysosomal pathway,and a reduced dynein-dynactin binding.展开更多
The South Central Axis in Beijing showcases China’s image and highlights its cultural confidence.THE Central Axis is the centerpiece of the Chinese capital’s urban spatial layout.The southern extended section of the...The South Central Axis in Beijing showcases China’s image and highlights its cultural confidence.THE Central Axis is the centerpiece of the Chinese capital’s urban spatial layout.The southern extended section of the Central Axis,or the South Central Axis,stretches from the Yongdingmen Gate Tower in the north to the South Fifth Ring Road in the south.While being a strategic transport link facilitating the coordinated development of the Beijing-Tianjin-Hebei region,it also showcases China’s vision for the future and highlights its cultural confidence.展开更多
In intelligent transportation systems,object detection for a surveillance video is one of the important functions.The performance of existing surveillance video object detection algorithms is affected by the conflict ...In intelligent transportation systems,object detection for a surveillance video is one of the important functions.The performance of existing surveillance video object detection algorithms is affected by the conflict between the features of the objects,which leads to a decline in precision.Therefore,an object detection algorithm based on deep learning and salient feature fusion is proposed.The proposed method introduces a non-weight-sharing network to process the salient features of the image and fuse them with the features extracted from the red blue green branch.Different from the previous solutions,the salient feature extraction branch uses the boundary features and statistical features of the image and fuses the features of the two branches in the efficient layer aggregation networks structure.At the same time,the attention module is used in efficient layer aggregation networks with convolutional block attention module to improve the efficiency of feature utilisation.The training and evaluation are carried out in the constructed surveillance video feature conflict dataset,and eight scenes are constructed in the way of orthogonal experiments.The experimental results show that the performance of object detection can be significantly improved by using the proposed method in the object detection task of the intelligent transportation system surveillance video feature conflict scene.展开更多
Water transport time lag in the Soil-Plant-Atmosphere Continuum(SPAC)significantly impacts ecosystem hydrology and plant water relations,yet the relative contributions of different segments(soil vs.plant)to the total ...Water transport time lag in the Soil-Plant-Atmosphere Continuum(SPAC)significantly impacts ecosystem hydrology and plant water relations,yet the relative contributions of different segments(soil vs.plant)to the total lag and their response mechanisms under drought remain unclear.This study aimed to quantitatively partition the total SPAC water transport time lag through controlled experiments,identify the dominant component driving the drought response,and compare coexisting tree species with contrasting hydraulic strategies:Platycladus orientalis and Quercus variabilis.We conducted potted plant isotope(δ^(2)H)labeling experiments under normal water and drought stress treatments for both species.Using high-frequency isotope sampling and synchronous sap flow monitoring,we quantified the total water transport time lag from the soil surface to canopy branches(T_(iso),based on initial isotope arrival)and the internal plant transport time lag(T_(sap),based on sap flow path integration).An independent laboratory soil mixing experiment determined the baseline soil mixing time lag(T_(mix)),and the lag associated with soil infiltration and root uptake initiation was estimated(T_(soil)=T_(iso)−T_(sap)).The physical mixing of old and new soil water introduced a baseline time lag(T_(mix))of approximately 8-12 h.Under normal water conditions,the internal plant lag(T_(sap):37-40 h)constituted the major part of the total lag(T_(iso):43-46 h),with the estimated soil process lag(T_(soil))being relatively short(3-9 h).Drought stress significantly prolonged the total time lag.Crucially,this increase was primarily driven by a dramatic increase in the internal plant transport time lag(T_(sap)):T_(sap) increased by 77 h(193%)for P.orientalis and 33 h(89%)for Q.variabilis.In contrast,the estimated soil process lag(T_(soil))showed minimal increase(or even decreased)under drought.Consequently,the increase in T_(sap) almost entirely accounted for the prolongation of T_(iso)(T_(iso) increased by 188%for P.orientalis and 63%for Q.variabilis).Furthermore,the shallow-rooted P.orientalis was more sensitive to drought in terms of internal time lag increase compared to the deep-rooted Q.variabilis.Our direct experimental evidence demonstrates that internal plant physiological and hydraulic processes,rather than soil processes,dominantly regulate the response of total SPAC water transport time lag to drought stress.Tree species with different hydraulic strategies exhibit distinct time lag response mechanisms.These findings challenge traditional perspectives potentially overemphasizing soil limitations and highlight the critical importance of understanding internal plant dynamics for accurately predicting the temporal responses of ecosystem water relations.展开更多
Microplastics are becoming well-known as chronic pollutants of terrestrial ecosystems,although their sources,dynamics of transportation,reliability of detection and ecological hazard are not evenly described.This revi...Microplastics are becoming well-known as chronic pollutants of terrestrial ecosystems,although their sources,dynamics of transportation,reliability of detection and ecological hazard are not evenly described.This review is a synthesis of the existing information about microplastics in soils,including analytical detection and characterization techniques,the major sources in the terrestrial environment,transport routes within the compartments and between compartments,and reported ecotoxicological consequences on soil biota,plants,and microbial communities.We also critically discuss the strengths and weaknesses of methodologies,making the distinction of sampling design differences,size detection limits,polymer identification methods,and quality assurance procedures on data comparability and uncertainty.An important outcome of this review is the systematic evaluation of the strength of evidence in three interrelated areas:measurement,environmental transport,and biological impacts,hence explaining which findings are strong and in which areas of research significant knowledge gaps still exist.We also suggest a conceptual framework that strongly connects the measurement uncertainty to the exposure estimation,interpretation of risk,and management relevance.This review uses mechanistic insights into transport and ecotoxicology alongside analysis constraints to add to the more comprehensive foundation of terrestrial risk assessment.Lastly,we determine research priorities,such as harmonized methodologies,realistic exposure scenarios,and cross-scale monitoring strategies,in order to assist in the science-based policies and mitigation action.展开更多
The plant pathogenic fungus Sclerotinia sclerotiorum is the causative agent of Sclerotinia stem rot(SSR)disease in most dicotyledons.Among the various proteins involved in drug efflux or substance transport,ATP-bindin...The plant pathogenic fungus Sclerotinia sclerotiorum is the causative agent of Sclerotinia stem rot(SSR)disease in most dicotyledons.Among the various proteins involved in drug efflux or substance transport,ATP-binding cassette(ABC)transporters constitute a superfamily of membrane-bound proteins that may play a crucial role in the survival of S.sclerotiorum.However,the expression patterns and functions of ABC transporter genes in S.sclerotiorum remain largely uncharacterized.This study characterized a highly expressed S.sclerotiorum ABC transporter gene during inoculation on host plants,Ss BMR1.Silencing Ss BMR1 resulted in a significant reduction in hyphal growth,infection cushion development,sclerotia formation,and virulence.Moreover,host-induced gene silencing(HIGS)of Ss BMR1 significantly enhanced plant resistance.Transcriptome and metabolomics analyses suggested that Ss BMR1 is involved in antioxidant and toxin transport,thereby influencing fungal defense and cell rescue mechanisms.In comparison to the wild-type strain,Ss BMR1 gene-silenced transformants exhibited a diminished response to extracellar oxidative stress and a decreased exporting of antioxidant glutathione.Tolerance assays further demonstrated the crucial role of Ss BMR1 in conferring resistance to the plant antifungal substances,camalexin and brassinin,as well as certain fungicides.Furthermore,Ss BMR1 gene-silenced transformants showed enhanced repression on virulence when sprayed with camalexin and brassinin on the leaves.Thus,Ss BMR1 likely contributes to virulence by facilitating the export of antioxidant and providing resistance against antifungal agents.The findings of this study provide valuable insights that could contribute to the development of novel management techniques for SSR.展开更多
The concept of Cyber-Physical Systems(CPS)enables the creation of a complex network that includes sensors integrated into vehicles and infrastructure,facilitating seamless data acquisition and transfer.This review exa...The concept of Cyber-Physical Systems(CPS)enables the creation of a complex network that includes sensors integrated into vehicles and infrastructure,facilitating seamless data acquisition and transfer.This review examines the convergence of CPS and Industry 4.0 in the smart transportation sector,highlighting their transformative impact on Intelligent Transportation Systems(ITS)operations.It explores the integration of Industry 4.0 and CPS technologies in intelligent transportation,highlighting their roles in enhancing efficiency,safety,and sustainability.A systematic framework is proposed for developing,implementing,and managing these technologies in the transportation industry.Moreover,the review discusses frequent obstacles during technology integration in transportation and presents future research trends and innovations in intelligent transportation operations post-Industry 4.0 and CPS integration.Lastly,it emphasizes the critical need for standardized protocols and encryption methodologies to enhance the security of communication and data exchange among CPS components in transportation infrastructure.展开更多
基金jointly sponsored by scientific research foundation NUPTSF(Grant No.NY-214144 and Grant No.NY-215073)NSFC(Grant No.61701260)
文摘Two-axis transportable satellite antennas(TATSAs) have been widely adopted owing to its simple structure and low cost. However, by searching in a wide range, it will take a very long searching time. Under extreme conditions, it will even fail to work. In this paper, we propose a novel roll compensation(RC) method for the low-cost TATSAs to achieve faster tracking even if when the antenna has no azimuth sensor. By analyzing the influence of roll axis on the system performance, details of the compensation method are derived. Simulation and measurement results indicate that the proposed RC method can effectively reduce the initial searching time for satellite communication. In addition, tracking along with the ellipse path with the RC method provides the highest tracking efficiency.
基金Supported by the National Natural Science Foundation of China under Grant No 91536217the West Light Foundation of the Chinese Academy of Sciences under Grant No 2013ZD02the Youth Innovation Promotion Association of the Chinese Academy of Sciences under Grant No 2015334
文摘We present two cavity-stabilized lasers at 1555 nm, which are built to be the frequency source for a transportable photonic microwave generation system. The frequency instability reaches the thermal noise limit （7 ×10-16） of the 10-cm ultra-low expansion glass cavity at 1-10s averaging time and the beat signal of the two lasers reveals a remarkable linewidth of 185mHz.
基金Project supported by the Basic Frontier Science Research Program of Chinese Academy of Sciences (Grant No.ZDBS-LY-DQC028)the National Key Research and Development Program of China (Grant No.2017YFA0304404)the National Natural Science Foundation of China (Grant No.11674357)。
文摘We report an experimental demonstration of geopotential difference measurement using a pair of transportable ^(40)Ca^(+) optical clocks(TOC-729-1 and TOC-729-3)in the laboratory,each of them has an uncertainty of 1.3×10^(−17) and an instability of 4.8×10^(−15)/√τ.Referenced to a stationary clock of TOC-729-1,the geopotential difference measurements are realized by moving TOC-729-3 to three different locations and the relevant altitude differences are measured with uncertainties at the level of 20 cm.After correcting the systematic shifts(including gravitational red shift),the two-clock frequency difference is measured to be–0.7(2.2)×10^(−17),considering both the statistic(1.0×10^(−17))and the systematic(1.9×10^(−17))uncertainties.The frequency difference between these two clocks is within their respective uncertainties,verifying the reliability of transportable ^(40)Ca^(+) optical clocks at the low level of 10^(−17).
文摘This paper studies single-parent family conversation mainly,the researcher takes 10 hours of recordings in a single-parent family in Shenzhen as data to study conversational identity construction.
基金supported by National Natural Science Foundation of China(No.72171026).
文摘This paper proposes a new method for service restoration of distribution network with the support of transportable power sources(TPSs)and repair crews(RCs).Firstly,a coupling model of distribution networks and vehicle routing of TPSs and RCs is proposed,where the TPSs serve as emergency power supply sources,and the RCs are used to repair the faulted lines.Considering the uncertainty of traffic congestion,the probability distribution of the travel time spent on each road is derived based on the Nesterov user equilibrium model,and a two-stage stochastic program is formulated to determine the optimal routings of TPSs and RCs.To efficiently solve the proposed stochastic mixed-integer linear program(MILP),a two-phase scenario reduction method is then developed to scale down the problem size,and an adaptive progressive hedging algorithm is used for an efficient solution.The effectiveness of the proposed methods and algorithms has been illustrated in a modified IEEE 33-bus system.
基金supported by the Ministry of Science and Technology of China(No.2013YQ09094304)the National Natural Science Foundation of China(No.11034008)
文摘A high-performance transportable fountain clockis attractive for use in laboratories with high-precisiontime-frequency measurement requirements. This Letterreports the improvement of the stability of atransportable rubidium-87 fountain clock because of anoptimization of temperature characteristics. This clockintegrates its physical packaging, optical benches,microwave frequency synthesizers, and electronic controlsonto an easily movable wheeled plate. Two optical bencheswith a high-vibration resistance are realized in thiswork. No additional adjustment is required after movingthem several times. The Allan deviation of the fountainclock frequency was measured by comparing it with that ofthe hydrogen maser. The fountain clock got a short-termstability of 2.3×10^-13 at 1 s and long-term stabilityon the order of 10-16 at 100,000 s.
基金financial support of the National Key R&D Program of China(Grant Nos.2024YFB4607402 and 2016YFA0200500)National Natural Science Foundation of China(NSFC,Grant Nos.61975213,61475164 and 61205194)International Partnership Program of Chinese Academy of Sciences(GJHZ2021130)。
文摘Microrobots play an essential role in early diagnosis and precision medicine with the increasing demands for controllability in bio-medicine and micromanipulation,which can complete the pre-designed behavior under external stimulation.However,most microrobots are currently made of a single material system and focus on fabricating a driving module as the main structure of microrobots.This hinders the integration of diverse functions in one microrobot to fulfill the complex application.Here,a multi-material and multi-module hand-microrobot based on femtosecond laser direct writing technology is proposed,which has a pH-responsive capturing module and a magnetic-responsive transportation module(MRTM).This microrobot can not only respond to pH for capturing and releasing objects,but also respond to magnetic fields for cargo delivery even with obstacles.The two responding modules of the hand-microrobot are fabricated independently,and can collaborate with each other to achieve the delivery of target objects like polystyrene(PS)microsphere(10µm)or 786-O cell by capturing,transporting,and spatial rolling.Besides,the MRTM can be locally fabricated on any prefabricated static structure,so that the whole microrobot can achieve controllable motion.This strategy is expected to be used to manipulate cells,deliver drugs for precise treatment,and environmental treatment.
文摘Noncohesive particle clusters are identified and tracked in turbulent flows to determine the breakdown and time evolution of cluster statistics and their implications for interscale mass transfer,which has connections to the classical turbulent energy cascade and its mass cascade counterpart running in parallel.In particular,the formation and dynamics of sediment and larvae clusters are of interest to coral larvae settlement in coastal regions and particularly the resilience of green-gray coastal protection solutions.Analogous cluster behavior is relevant to cloud microphysics and precipitation initiation,radiation transport and light transmission through colloids and suspensions,heat and mass transfer in particle-laden flows,and viral and pollutant transmission.Following a comparison between various clustering techniques,we adopt a density-based cluster identification algorithm based on its simplicity and efficiency,where particles are clustered based on the number of neighboring particles in their individual spheres of influence.We establish parallels with lattice-based percolation theory,as evident in the power-law scaling of the cluster size distribution near the percolation threshold.The degree of discontinuity of the phase transition associated with this percolation threshold is observed to broaden with larger Stokes numbers and thereby large-scale clustering.The sensitivity of our findings to the employed clustering algorithm is discussed.A novel cluster tracking algorithm is deployed to determine the interscale transfer rate along the particle-number phase-space dimension via accounting of cluster breakup and merger events,extending previous work on the bubble breakup cascade beneath surface breaking waves.Our findings shed light on the interaction between particle clusters and their carrier turbulent flows,with an eye toward transport models incorporating cluster characteristics and dynamics.
文摘The longitudinal π-extension of carbon nanohoops is one of the most effective bottom-up synthetic strategies toward carbon nanotubes(CNTs).Herein,the precise synthesis of a multi-substituted carbon nanohoop([12]CPP-8PBPy)based on cycloparaphenylenes(CPPs)grafted with eight pyrene-functionalized units was reported.This structurally well-defined nanohoop not only acts as a segment of armchair-type CNTs but also achieves enhanced longitudinal π-extension.The structure of[12]CPP-8PBPy was confirmed by high-resolution mass spectrometry(HRMS)and nuclear magnetic resonance(NMR).The photophysical properties were studied by UV/Vis and photoluminescence spectroscopy.The potential applications of[12]CPP-8PBPy in electron-transport devices were further investigated.
基金Special Fund for Key Technologies in Blockchain of Shanghai Scientific and Technological Committee(23511100300)。
文摘Post-quantum transport layer security(PQ-TLS)is capable of effectively defending against quantum threats to current network communications,whereas its larger public key and certificate sizes as well as higher computational overhead may result in a significant performance reduction compared with conventional TLS.In this paper,we present a systematic evaluation of PQ-TLS performance across diverse deployment scenarios to address the following critical research questions.(1)What is the performance behavior of PQ-TLS across different TLS modes?(2)How does PQ-TLS perform across varying client scales?(3)Which network topology is most suitable for PQ-TLS?(4)How does PQ-TLS perform on personal computers(PCs)compared to embedded IoT devices?To the best of our knowledge,this is the first work to comprehensively address these issues,offering implementers some insights into PQ-TLS performance and guidance for optimizing it across diverse scenarios.
基金Supported by the National Natural Science Foundation of China(52004152)Shandong Provincial Natural Science Foundation(ZR2024ME006,ZR2023QE133,ZR2020QE100)+2 种基金Small and Medium-sized Technology Enterprises in Shandong Province(2022TSGC2077)Shandong College Youth Science and Technology Support Program(2023KJ149)National Key Laboratory Open Project Open Fund(2023-JSKSSYS-06)。
文摘This research conducts a comprehensive experimental study of the entire filling system process at the Weishan Lake Rare Earth Mine(WSLREM)in Shandong Province,encompassing tailings thickening,feeding,slurry preparation,and pipeline transportation.It proposes a complete and efficient upgrade solution for an intelligent paste filling system.The results show that the F1 flocculant was selected to prepare a flocculant solution with a solution concentration of 0.1%.The unit consumption is set to 25 g·t^(-1),and the flocculation and sedimentation effects are optimal when the mass concentration is 15%,with an underflow concentration of 62%.The selection experiment of cementitious material shows that the effect of using new cementitious material is better than that of traditional 32.5R Portland cement.At the same time,rheological experiments on the filling slurry were carried out,and the filling transportation pressure was studied by combining theoretical calculations with numerical simulations.The research results have guiding significance for the debugging of filling pumps and the selection of a filling pipeline.After the application of industrial transformation,the underflow concentration of the sand silo was 64%–66%,the slurry concentration was 68%–72%,the addition range of the cementing material was 1∶16–1∶4,and the filling capacity was 40–60 m^(3)·h^(-1).The intelligent upgrade and transformation of the filling system have yielded remarkable results,providing significant reference value for the intelligent filling transformation of similar mines.
文摘Purpose-This paper provides a comprehensive analysis of the Brazilian freight railway system,examining the efficacy of the current concession renewal model in light of persistent structural problems such as market concentration,cargo dependence on export commodities and underutilization of the network.Situating Brazil within the broader international debate on railway reforms,the paper evaluates whether the ongoing early renewal of concessions can deliver a more diversified and competitive freight system.Design/methodology/approach-The study adopts a sequential mixed-methods research design that integrates longitudinal quantitative analysis with qualitative institutional and policy evaluation.The quantitative component examines time-series indicators published by ANTT,DNIT and INFRA S.A.from 1999 to 2023 to identify structural patterns in traffic growth,investment,safety and market concentration.The qualitative component employs a process-tracing logic to reconstruct the evolution of concession renewals and the implementation of Railway Law 14.273/2021,drawing on concepts from regulatory economics,institutional theory and industrial organization.These empirical streams are synthesized through an analytical framework that connects three dimensions-regulatory design,market structure and system performance-allowing for a systematic assessment of how Brazil’s institutional configuration shapes incentives,competitive dynamics and network utilization.Findings-The analysis confirms that the early renewal of concessions has successfully secured substantial private investment for capacity expansion on existing trunk lines.However,it has perpetuated the vertically integrated model,reinforcing the market power of incumbent operators and failing to significantly promote intramodal competition or cargo diversification.The system remains dominated by iron ore and agricultural commodities,with general cargo representing a minuscule share.The new authorization regime and short-line railway policies present a viable pathway for market opening but face significant operational and institutional barriers to implementation.Originality/value-This research offers a timely and critical assessment of a pivotal moment in Brazilian railway policy.It moves beyond a simplistic evaluation of volume growth to a structural analysis of market failures and the interplay between concession renewal and regulatory innovation.The findings provide actionable insights for policymakers in Brazil and other emerging economies seeking to balance private investment with public interest goals in railway infrastructure,highlighting the necessity of complementary,pro-competitive measures alongside financial investment.
基金supported by the National Natural Science Foundation of China(Grant Nos.32560065 and 32572249)the Guizhou Provincial Excellent Young Talents Project of Science and Technology,China(Grant No.qiankehepingtairencai-YQK(2023)002)+4 种基金the Guizhou Provincial Science and Technology Projects,China(Grant Nos.qiankehechengguo(2024)General 116 and qiankehejichu-ZK(2022)Key 008)the Key Laboratory of High Quality,High Efficiency,and Yield Enhancement in Grain and Oil Crops,China(Grant No.Qiankehe-Platform ZSYS(2025)037)the Key Laboratory of Functional Agriculture of Guizhou Provincial Department of Education,China(Grant No.Qianjiaoji(2023)007)Guizhou Provincial Modern Agricultural Industry Technology System Construction Special Program(Grant No.GZSDCYJSTX-202602)the Qiandongnan Science and Technology Support Project,China(Grant No.Qiandongnan Kehe Support(2023)07).
文摘Synergistically improving the yield and grain quality of rice remains a major breeding challenge.Amino acid transporters play key roles in regulating plant growth and development,but their mechanisms in synergistically regulating yield and quality remain unclear.Here,we report that the plasma membrane-localized transporter OsAAP18,which is more highly expressed in indica than japonica rice,positively correlates with tiller number and yield but negatively with grain width.OsAAP18 transports eight amino acids,including asparagine(Asn),proline(Pro),leucine(Leu),and valine(Val).Its overexpression increases yield through enhanced tillering and grain number per panicle while also improving rice processing and cooking quality.Transcriptome analysis showed that OsAAP18 coordinates grain development and quality formation by regulating the expression of key genes involved in starch and sucrose metabolism,nitrogen metabolism,and plant hormone signaling pathways.These findings establish OsAAP18 as a dual-function regulator that synergistically enhances yield and quality,offering a promising target for rice breeding.
基金China Scholarship Council(CSCto XL)and a generous heritage donation from Bettina Fischer,Germany(to JCK).
文摘Aging is characterized by a decreased autophagic activity contributing to the intracellular deposition of damaged organelles and macromolecules.Autophagy is particularly challenging in neurons since autophagic vesicles are formed at the axonal tip and must be transported to the soma where final degradation occurs.Here,we examined if axonal transport of autophagic vesicles is altered during aging.We employed two-photon microscopy for in vivo imaging in the optic nerve of young and aged rats.In old animals(>18 months old),retrograde autophagic vesicle transport was significantly reduced with regard to motility and velocity.While activation of autophagy was decreased,expression of key proteins of the autophagy-lysosomal pathway including p62 and procathepsin D and the number of autophagolysosomes was increased.Maturation of autophagic vesicles was shifted to more distal regions of the axon and axonal lysosomal clearing was impaired.In a pull-down assay,the protein binding between dynein and dynactin was decreased by half,which could explain the retrograde axonal transport effects.Taken together,retrograde axonal autophagic vesicle transport in vivo is diminished during aging accompanied by decreased autophagy activation,alterations of the lysosomal pathway,and a reduced dynein-dynactin binding.
文摘The South Central Axis in Beijing showcases China’s image and highlights its cultural confidence.THE Central Axis is the centerpiece of the Chinese capital’s urban spatial layout.The southern extended section of the Central Axis,or the South Central Axis,stretches from the Yongdingmen Gate Tower in the north to the South Fifth Ring Road in the south.While being a strategic transport link facilitating the coordinated development of the Beijing-Tianjin-Hebei region,it also showcases China’s vision for the future and highlights its cultural confidence.
基金supported by the National Key Research and Development Programme of China(2021YFB3202200)the National Natural Science Foundation of China(52072333)Hebei Provincial Department of Education in the postgraduate innovation ability training funding project(CXZZBS2023061).
文摘In intelligent transportation systems,object detection for a surveillance video is one of the important functions.The performance of existing surveillance video object detection algorithms is affected by the conflict between the features of the objects,which leads to a decline in precision.Therefore,an object detection algorithm based on deep learning and salient feature fusion is proposed.The proposed method introduces a non-weight-sharing network to process the salient features of the image and fuse them with the features extracted from the red blue green branch.Different from the previous solutions,the salient feature extraction branch uses the boundary features and statistical features of the image and fuses the features of the two branches in the efficient layer aggregation networks structure.At the same time,the attention module is used in efficient layer aggregation networks with convolutional block attention module to improve the efficiency of feature utilisation.The training and evaluation are carried out in the constructed surveillance video feature conflict dataset,and eight scenes are constructed in the way of orthogonal experiments.The experimental results show that the performance of object detection can be significantly improved by using the proposed method in the object detection task of the intelligent transportation system surveillance video feature conflict scene.
基金financial supports from the National Science Foundation of China(42277062,41977149 and 42230714).
文摘Water transport time lag in the Soil-Plant-Atmosphere Continuum(SPAC)significantly impacts ecosystem hydrology and plant water relations,yet the relative contributions of different segments(soil vs.plant)to the total lag and their response mechanisms under drought remain unclear.This study aimed to quantitatively partition the total SPAC water transport time lag through controlled experiments,identify the dominant component driving the drought response,and compare coexisting tree species with contrasting hydraulic strategies:Platycladus orientalis and Quercus variabilis.We conducted potted plant isotope(δ^(2)H)labeling experiments under normal water and drought stress treatments for both species.Using high-frequency isotope sampling and synchronous sap flow monitoring,we quantified the total water transport time lag from the soil surface to canopy branches(T_(iso),based on initial isotope arrival)and the internal plant transport time lag(T_(sap),based on sap flow path integration).An independent laboratory soil mixing experiment determined the baseline soil mixing time lag(T_(mix)),and the lag associated with soil infiltration and root uptake initiation was estimated(T_(soil)=T_(iso)−T_(sap)).The physical mixing of old and new soil water introduced a baseline time lag(T_(mix))of approximately 8-12 h.Under normal water conditions,the internal plant lag(T_(sap):37-40 h)constituted the major part of the total lag(T_(iso):43-46 h),with the estimated soil process lag(T_(soil))being relatively short(3-9 h).Drought stress significantly prolonged the total time lag.Crucially,this increase was primarily driven by a dramatic increase in the internal plant transport time lag(T_(sap)):T_(sap) increased by 77 h(193%)for P.orientalis and 33 h(89%)for Q.variabilis.In contrast,the estimated soil process lag(T_(soil))showed minimal increase(or even decreased)under drought.Consequently,the increase in T_(sap) almost entirely accounted for the prolongation of T_(iso)(T_(iso) increased by 188%for P.orientalis and 63%for Q.variabilis).Furthermore,the shallow-rooted P.orientalis was more sensitive to drought in terms of internal time lag increase compared to the deep-rooted Q.variabilis.Our direct experimental evidence demonstrates that internal plant physiological and hydraulic processes,rather than soil processes,dominantly regulate the response of total SPAC water transport time lag to drought stress.Tree species with different hydraulic strategies exhibit distinct time lag response mechanisms.These findings challenge traditional perspectives potentially overemphasizing soil limitations and highlight the critical importance of understanding internal plant dynamics for accurately predicting the temporal responses of ecosystem water relations.
文摘Microplastics are becoming well-known as chronic pollutants of terrestrial ecosystems,although their sources,dynamics of transportation,reliability of detection and ecological hazard are not evenly described.This review is a synthesis of the existing information about microplastics in soils,including analytical detection and characterization techniques,the major sources in the terrestrial environment,transport routes within the compartments and between compartments,and reported ecotoxicological consequences on soil biota,plants,and microbial communities.We also critically discuss the strengths and weaknesses of methodologies,making the distinction of sampling design differences,size detection limits,polymer identification methods,and quality assurance procedures on data comparability and uncertainty.An important outcome of this review is the systematic evaluation of the strength of evidence in three interrelated areas:measurement,environmental transport,and biological impacts,hence explaining which findings are strong and in which areas of research significant knowledge gaps still exist.We also suggest a conceptual framework that strongly connects the measurement uncertainty to the exposure estimation,interpretation of risk,and management relevance.This review uses mechanistic insights into transport and ecotoxicology alongside analysis constraints to add to the more comprehensive foundation of terrestrial risk assessment.Lastly,we determine research priorities,such as harmonized methodologies,realistic exposure scenarios,and cross-scale monitoring strategies,in order to assist in the science-based policies and mitigation action.
基金received financial support from the Natural Science Foundation of Chongqing,China(CSTB2023NSCQMSX0355)the Fundamental Research Funds for the Central Universities,China(SWU120075)the National Natural Science Foundation of China(32372077)。
文摘The plant pathogenic fungus Sclerotinia sclerotiorum is the causative agent of Sclerotinia stem rot(SSR)disease in most dicotyledons.Among the various proteins involved in drug efflux or substance transport,ATP-binding cassette(ABC)transporters constitute a superfamily of membrane-bound proteins that may play a crucial role in the survival of S.sclerotiorum.However,the expression patterns and functions of ABC transporter genes in S.sclerotiorum remain largely uncharacterized.This study characterized a highly expressed S.sclerotiorum ABC transporter gene during inoculation on host plants,Ss BMR1.Silencing Ss BMR1 resulted in a significant reduction in hyphal growth,infection cushion development,sclerotia formation,and virulence.Moreover,host-induced gene silencing(HIGS)of Ss BMR1 significantly enhanced plant resistance.Transcriptome and metabolomics analyses suggested that Ss BMR1 is involved in antioxidant and toxin transport,thereby influencing fungal defense and cell rescue mechanisms.In comparison to the wild-type strain,Ss BMR1 gene-silenced transformants exhibited a diminished response to extracellar oxidative stress and a decreased exporting of antioxidant glutathione.Tolerance assays further demonstrated the crucial role of Ss BMR1 in conferring resistance to the plant antifungal substances,camalexin and brassinin,as well as certain fungicides.Furthermore,Ss BMR1 gene-silenced transformants showed enhanced repression on virulence when sprayed with camalexin and brassinin on the leaves.Thus,Ss BMR1 likely contributes to virulence by facilitating the export of antioxidant and providing resistance against antifungal agents.The findings of this study provide valuable insights that could contribute to the development of novel management techniques for SSR.
文摘The concept of Cyber-Physical Systems(CPS)enables the creation of a complex network that includes sensors integrated into vehicles and infrastructure,facilitating seamless data acquisition and transfer.This review examines the convergence of CPS and Industry 4.0 in the smart transportation sector,highlighting their transformative impact on Intelligent Transportation Systems(ITS)operations.It explores the integration of Industry 4.0 and CPS technologies in intelligent transportation,highlighting their roles in enhancing efficiency,safety,and sustainability.A systematic framework is proposed for developing,implementing,and managing these technologies in the transportation industry.Moreover,the review discusses frequent obstacles during technology integration in transportation and presents future research trends and innovations in intelligent transportation operations post-Industry 4.0 and CPS integration.Lastly,it emphasizes the critical need for standardized protocols and encryption methodologies to enhance the security of communication and data exchange among CPS components in transportation infrastructure.
