The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key...The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key technologies for ensuring the success of rocket flights and has been a core topic in carrier rocket technology research. The Gravity-1 solid carrier rocket is the first solid rocket bundled rocket developed by China, adopting a configuration with four boosters and a core stage bundled together. During the actual flight process, the four booster engines are ignited first, and then, in the event of insufficient control force from the boosters, the core stage engine is ignited to participate in control. To address thrust asynchrony during the descent of the four boosters, an Extended State Observer(ESO) is employed in the control scheme for this flight segment. This involves real-time estimation and compensation of attitude parameters during flight, identification of thrust asynchrony among the boosters, and simultaneous determination of whether the core stage engine is ignited to participate in control.Through six degrees of freedom simulation analysis and Y1 flight test validation, this method has been proven to be correct and feasible.展开更多
In this paper, the asynchrony problem of distributed detection is analyzed and discussed.Two approaches are proposed and related results are given. It is shown that all fusion rules can beunified in the framework with...In this paper, the asynchrony problem of distributed detection is analyzed and discussed.Two approaches are proposed and related results are given. It is shown that all fusion rules can beunified in the framework with asynchrony which could be much ciooer to industrial practice.展开更多
Patient–ventilator asynchrony in Saudi Arabia practices is common,and more emphasis on how to mitigate such a clinical problem is needed.This letter is intended to shed the light on the current national evidence of p...Patient–ventilator asynchrony in Saudi Arabia practices is common,and more emphasis on how to mitigate such a clinical problem is needed.This letter is intended to shed the light on the current national evidence of patient–ventilator asynchrony and how to step ahead for better patients'ventilation management.展开更多
Asymmetric seasonal warming,characterized by more pronounced temperature increases in winter than in summer,has become a critical feature of global warming,especially in cold and high-altitude regions.Previous studies...Asymmetric seasonal warming,characterized by more pronounced temperature increases in winter than in summer,has become a critical feature of global warming,especially in cold and high-altitude regions.Previous studies have primarily focused on year-round warming,while comparatively less attention was paid to winter warming.However,a significant knowledge gap exists regarding the impacts of winter warming on ecosystem functions.To address this,we conducted an 8-year manipulated warming experiment in an alpine grassland on the Tibetan Plateau,employing three treatments:no warming,year-round warming and winter warming.We found that neither year-round warming nor winter warming significantly alters species richness at the community level.Notably,community biomass stability was maintained via species asynchrony.However,warming exerted significant effects on the plant abundance groups(dominant,common and rare species).Specifically,winter warming enhanced the stability of dominant species by increasing species asynchrony of dominant species,as the compensatory dynamics occurred between the grass and forbs.In contrast,year-round warming reduced the stability of common species,correlated with an increase in species richness and a decline in asynchrony among common species.Thus,our study underscores the capacity of alpine grassland to maintain community biomass stability via asynchrony dynamics of species under different warming conditions,although the stability of different abundance groups would be changed.Importantly,our results provide valuable insights for understanding the alpine grassland ecosystem on the Tibetan Plateau.展开更多
In recent years,many studies have focused on the effects of global climate warming and increased nitrogen deposition on the structure and function of grassland ecosystem.However,there are still significant uncertainti...In recent years,many studies have focused on the effects of global climate warming and increased nitrogen deposition on the structure and function of grassland ecosystem.However,there are still significant uncertainties in the response mechanism of stability of plant community biomass in alpine meadows of the Qinghai-Xizang Plateau,China to these two major climate factors.Given this,based on field control experiments,this study systematically evaluated the effects of different levels of climate warming(W0(no warming),W1(air temperature increased by 0.47℃ or soil temperature increased by 0.61℃),W2(air temperature increased by 0.92℃ or soil temperature increased by 1.09℃),W3(air temperature increased by 1.44℃ or soil temperature increased by 1.95℃)),nitrogen deposition(N0(0 kg N/(hm^(2)·a)),N16(16 kg N/(hm^(2)·a)),and N32(32 kg N/(hm^(2)·a))),and their interactions on plant community biomass and its temporal stability,and explored its potential regulatory mechanisms.The results showed that the biomass of total community,Gramineae,and dominant species increased significantly with increasing temperature,but the biomass of common and rare species decreased significantly.Nitrogen deposition also significantly promoted the biomass accumulation of community and gramineous plants.Under the treatment of W3N32,the biomass of plant community,Gramineae,and dominant species reached the highest values,indicating that there was a synergistic effect under this treatment.Structural equation model showed that increasing temperature significantly decreased the stability of plant community biomass by reducing the stability of grass and dominant species biomass and weakening species asynchronism.Interaction of increased nitrogen deposition and temperature increased the biomass fluctuation of grass functional group,thus amplifying its negative influence on community stability.More attention should be paid to the response and regulatory mechanisms of dominant species and functional groups under global climate change.This study provides a theoretical basis for revealing the stability maintenance mechanism of alpine grassland and also provides scientific support for the development of future grassland ecosystem management and assessment.展开更多
In this paper, the relative phase relationship between flare index and sunspot activity （sunspot numbers and sunspot areas） is investigated. It is found that （i） the flare index and sunspot activity are asynchrono...In this paper, the relative phase relationship between flare index and sunspot activity （sunspot numbers and sunspot areas） is investigated. It is found that （i） the flare index and sunspot activity are asynchronous in phase space at all period scales, and the former lags behind the latter, which implies our results are supported for the integral response model; （ii） their different definitions and physical meanings may be a major reason for their phase asynchrony between them, and the solar flare activity favor to be related to the magnetic complex rather than magnetic strength.展开更多
Host-mediated effects on hemiparasitic mistletoes were hypothesized to contribute to mistletoes reproductive phenological asynchrony,thus providing a longer period of food supply to its mutualistic pollinators and dis...Host-mediated effects on hemiparasitic mistletoes were hypothesized to contribute to mistletoes reproductive phenological asynchrony,thus providing a longer period of food supply to its mutualistic pollinators and dispersers.However,studies with empirical data interrogating this hypothesis are lacking.Weekly monitoring of flowering and fruiting patterns on a generalist mistletoe Dendrophthoe pentandra(Loranthaceae)was conducted for two consecutive years in tropical Xishuangbanna,Southwest China.We examined whether flowering and fruiting patterns were seasonal,quantified the degree of stagger within D.pentandra populations and determined the factors influencing the first flowering date(FFD)of D.pentandra.Furthermore,the effect of change in the number of host species on reproductive phenological asynchrony of mistletoe was examined.We found that(i)both flowering and fruiting exhibited unimodal peaks in the two consecutive years of the study;(ii)the FFD was significantly influenced by crown area of mistletoe and light,such that clump with larger crown and more light exposure had an earlier FFD and longer flowering and fruiting durations;(iii)different host species had a significant impact on the phenology of mistletoes.However,contrary to our hypothesis,the number of host species did not significantly change the asynchrony of reproductive phenology of mistletoe.Therefore,these results suggest that alternative hypotheses are needed to interpret the ecological significance of the number of host species and phenological asynchrony of generalist mistletoes.展开更多
The mechanism that sustains the temporal stability of aboveground net primary production(ANPP)respond to nitrogen deposition is still controversial.Consequently,we investigated the mechanism of temporal stability of A...The mechanism that sustains the temporal stability of aboveground net primary production(ANPP)respond to nitrogen deposition is still controversial.Consequently,we investigated the mechanism of temporal stability of ANPP through the effect of N addition on diversity,species asynchrony andportfolio effects in northern Tibet alpine steppe over a period of three years.Our results showed that the community temporal stability did not significantly correlate with the species richness and Shannon–Wiener diversity.Species asynchrony and stability was also not significantly affected by N addition(p>0.05).Furthermore,there was no significant relationship between species asynchrony and temporal stability.Although the value of portfolio effects(z)(z=1.304,95%confidence intervals:1.029–1.597)was more than 1,the portfolio effects was not a primary driver of temporal stability due to the biodiversity being unaffected.The above results suggested that the richness,species asynchrony and portfolio effect could not support for mechanism of stability at the alpine steppe.From the results of path analysis,species temporal stability positively supports the community temporal stability in the alpine steppe ecosystem.According to the character of environment and vegetation of alpine steppe at North Tibet,we inferred that dominance species stability is more important than species richness for the community temporal stability.展开更多
Deciduous trees with high-density wood that occur in dry seasonal tropical regions respond to rainfall seasonality with synchrony in phenophases. However, they may exhibit interannual differences in synchrony and inte...Deciduous trees with high-density wood that occur in dry seasonal tropical regions respond to rainfall seasonality with synchrony in phenophases. However, they may exhibit interannual differences in synchrony and intensity of phenophases, as strategy for large variations in duration and intensity of rainfall pulses. Nevertheless, it remains unknown how phenophases of deciduous trees of the Brazilian semi-arid region respond to rainfall variations. The phenology of Cordia oncocalyx was monitored in deciduous thorny woodland （Caatinga）, from April 2009 to March 2011, and was correlated with rainfall, soil humidity, temperature, and photoperiod. The rainy years 2009 and 2011 exhibited higher duration of rainfall pulses and lower frequency of interpulses, but in 2010 pulse duration and total rainfall were lower. Circular statistics showed leaf flush followed by flowering and fruiting in the rainy season, and leaf fall and seed dispersal in the dry season.展开更多
Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sati...Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sativus, 2n = 2x = 14) and its relative C. hystrix(2n = 2x = 24) followed by chemical induction of chromosome doubling. The resulting allotetraploid plant was self-pollinated for three generations. The fertility and seed set of the amphidiploid plants were very low. In this study, we investigated the meiotic chromosome behavior in pollen mother cells with the aid of fluorescence in situ hybridization, aiming to identify the reasons for the low fertility and seed set in the amphidiploid plants. Homologous chromosome pairing appeared normal, but chromosome laggards were common, owing primarily to asynchronous meiosis of chromosomes from the two donor genomes. We suggest that asynchronous meiotic rhythm between the two parental genomes is the main reason for the low fertility and low seed set of the C. hystrix–cucumber amphidiploid plants.展开更多
Inbreeding negatively affects various life-history traits, with inbred individuals typically having lower fit- ness than outbred individuals （=inbreeding depression）. Inbreeding depression is often emphasized under ...Inbreeding negatively affects various life-history traits, with inbred individuals typically having lower fit- ness than outbred individuals （=inbreeding depression）. Inbreeding depression is often emphasized under environmental stress, but the underlying mechanisms and potential long-lasting consequences of such inbreeding-environment interactions remain poorly understood. Here, we hypothesize that inbreeding-environment interactions that occur early in life have long-term physiological effects, in partic- ular on the adult oxidative balance. We applied a unique experimental design to manipulate early life conditions of inbred and outbred songbirds （Serinus canaria） that allowed us to separate prenatal and postnatal components of early life conditions and their respective importance in inbreeding-environment interactions. We measured a wide variety of markers of oxidative status in adulthood, resulting in a com- prehensive account for oxidative balance. Using a Bayesian approach with Markov chain Monte Carlo, we found clear sex-specific effects and we also found only in females small yet significant long-term effects of inbreeding-environment interactions on adult oxidative balance. Postnatal components of early life conditions were most persuasively reflected on adult oxidative balance, with inbred females that experienced disadvantageous postnatal conditions upregulating enzymatic antioxidants in adulthood. Our study provides some evidence that adult oxidative balance can reflect inbreeding-environment inter- actions early in life, but given the rather small effects that were limited to females, we conclude that oxida- tive stress miaht have a limited role as mechanism underlvina inhre.e.dina-envirnnme.nt inte.raetinn.q_展开更多
Sibling cannibalism is relatively common in nature,but its evolution in birds and certain other vertebrates with extended parental care had been discarded.Here,however,we demonstrate its regular occurrence in two Euro...Sibling cannibalism is relatively common in nature,but its evolution in birds and certain other vertebrates with extended parental care had been discarded.Here,however,we demonstrate its regular occurrence in two European populations of the Eurasian hoopoe(Upupa epops)and explore possible adaptive and non-adaptive explanations.Results showed that sibling cannibalism was more frequently detected in Spain(51.7%)than in Austria(5.9%).In these two populations,the hoopoes laid similar clutch sizes,resulting in similar fledging production,but hatching failures were more frequent in the northern population.Consequently,having more nestlings condemned to die in the southern population may explain the higher incidence of sibling cannibalism.In accordance with this interpretation,hatching span and failure,but not breeding date,explained the probability of sibling cannibalism in the Spanish hoopoes,while all three variables predicted brood reduction intensity.Furthermore,experimental food supply reduced the probability of sibling cannibalism,but not the intensity of brood reduction.Finally,females allocated fewer resources to the smallest nestlings when they were going to starve,but not necessarily when they were going to be used as food for their siblings.These results suggest that hoopoes produce extra eggs that,in the case of reduced hatching failure and food scarcity,produce nestlings that are used to feed older siblings.These findings provide the first evidence that sibling cannibalism occurs regularly in a bird species,thus expanding our evolutionary understanding of clutch size,hatching asynchrony,parent-offspring conflict,infanticide,and sibling cannibalism in the animal kingdom.展开更多
This paper proposes a hierarchical dual-horizon preview control strategy for semi-active suspensions with CDC dampers and dual-chamber air springs.To address the preview information uncertainties and actuator delay,th...This paper proposes a hierarchical dual-horizon preview control strategy for semi-active suspensions with CDC dampers and dual-chamber air springs.To address the preview information uncertainties and actuator delay,the upper layer employs a tube-based model predictive controller using long-horizon preview information,while the lower layer uses shorthorizon preview with a GRNN-based delay model to adjust the preview window in real time.A frequency-domain force separation approach is introduced to synchronize the actuator response.Experimental results show up to 50.49% improvement in suspension force tracking under Class-C road conditions,validating the effectiveness of the proposed method in enhancing ride comfort and actuator coordination under uncertainty.展开更多
Three-dimensional(3D)imaging with structured light is crucial in diverse scenarios,ranging from intelligent manufacturing and medicine to entertainment.However,current structured light methods rely on projector-camera...Three-dimensional(3D)imaging with structured light is crucial in diverse scenarios,ranging from intelligent manufacturing and medicine to entertainment.However,current structured light methods rely on projector-camera synchronization,limiting the use of affordable imaging devices and their consumer applications.In this work,we introduce an asynchronous structured light imaging approach based on generative deep neural networks to relax the synchronization constraint,accomplishing the challenges of fringe pattern aliasing,without relying on any a priori constraint of the projection system.To overcome this need,we propose a generative deep neural network with U-Net-like encoder-decoder architecture to learn the underlying fringe features directly by exploring the intrinsic prior principles in the fringe pattern aliasing.We train within an adversarial learning framework and supervise the network training via a statisticsinformed loss function.We demonstrate that by evaluating the performance on fields of intensity,phase,and 3D reconstruction.It is shown that the trained network can separate aliased fringe patterns for producing comparable results with the synchronous one:the absolute error is no greater than 8μm,and the standard deviation does not exceed 3μm.Evaluation results on multiple objects and pattern types show it could be generalized for any asynchronous structured light scene.展开更多
Aims Long-term heavy grazing reduces plant diversity and ecosystem function by intensifying nitrogen(N)and water limitation.In contrast,the absence of biomass removal can cause species loss by elevating light competit...Aims Long-term heavy grazing reduces plant diversity and ecosystem function by intensifying nitrogen(N)and water limitation.In contrast,the absence of biomass removal can cause species loss by elevating light competition and weakening community stability,which is exacerbated by N and water enrichment.Hence,how to maintain species diversity and community stability is still a huge challenge for sustainable management of worldwide grasslands.Methods We conducted a 4-year manipulated experiment in six long-term grazing blocks to explore combination of resource additions and biomass removal(increased water,N and light availability)on species richness and community stability in semiarid grasslands of Inner Mongolia,China.Important Findings In all blocks treated with the combination of resource additions and biomass removal,primary productivity increased and species richness and community stability were maintained over 4 years of experiment.At both species and plant functional group(PFG)levels,the aboveground biomass of treated plants remained temporally stable in treatments with the combination of N and/or water addition and biomass removal.The maintenance of species richness was primarily caused by the biomass removal,which could increase the amount of light exposure for grasses under resource enrichment.Both species asynchrony and stability of PFGs contributed to the high temporal stability observed in these communities.Our results indicate that management practices of combined resource enrichment with biomass removal,such as grazing or mowing,could not only enhance primary productivity but also maintain plant species diversity,species asynchrony and community stability.Furthermore,as overgrazing-induced degradation and resource enrichment-induced biodiversity loss continue to be major problems worldwide,our findings have important implications for adaptive management in semiarid grasslands and beyond.展开更多
Nitrogen enrichment and land use are known to influence various ecosystems,but how these anthropogenic changes influence community and ecosystem responses to disturbance remains poorly understood.Here we investigated ...Nitrogen enrichment and land use are known to influence various ecosystems,but how these anthropogenic changes influence community and ecosystem responses to disturbance remains poorly understood.Here we investigated the effects of increased nitrogen input and mowing on the resistance and recovery of temperate semiarid grassland experiencing a three-year drought.Nitrogen addition increased grassland biomass recovery but decreased structural recovery after drought,whereas annual mowing increased grassland biomass recovery and structural recovery but reduced structural resistance to drought.The treatment effects on community biomass/structural resistance and recovery were largely modulated by the stability of the dominant species and asynchronous dynamics among species,and the community biomass resistance and recovery were also greatly driven by the stability of grasses.Community biomass resistance/recovery in response to drought was positively associated with its corresponding structural stability.Our study provides important experimental evidence that both nitrogen addition and mowing could substantially change grassland stability in both functional and structural aspects.Our findings emphasize the need to study changes across levels of ecological organization for a more complete understanding of ecosystem responses to disturbances under widespread environmental changes.展开更多
In this paper we devote ourselves to the study of the asymptotic behavior of a size-structured pop- ulation dynamics with random diffusion and delayed birth process. Within a semigroup framework, we discuss the local ...In this paper we devote ourselves to the study of the asymptotic behavior of a size-structured pop- ulation dynamics with random diffusion and delayed birth process. Within a semigroup framework, we discuss the local stability and asynchrony respectively for the considered population system under some conditions. We use for our discussion the techniques of operator matrices, Hille-Yosida operators, positivity, spectral analysis as well as Perron-Frobenius theory.展开更多
Nitrogen(N)deposition decreases the temporal stability of ecosystem aboveground biomass production(ecosystem stability).However,little is known about how the responses of ecosystem stability differ based on seasonal N...Nitrogen(N)deposition decreases the temporal stability of ecosystem aboveground biomass production(ecosystem stability).However,little is known about how the responses of ecosystem stability differ based on seasonal N enrichment.By adding N in autumn,winter,or growing season,from October 2014 to May 2020,in a temperate grassland in northern China,we found that only N addition in autumn resulted in a significantly positive correlation between ecosystem mean aboveground net primary productivity(ANPP)and its standard deviation and significantly reduced ecosystem stability.Autumn N-induced reduction in ecosystem stability was associated with the vanished negative effect of community-wide species asynchrony(asynchronous dynamics among populations to environmental perturbations)on the standard deviation of ecosystem ANPP in combination with the emerged positive effect of dominance(Simpson's dominance index that indicates the relative weight of dominant species in a community).Our findings indicate that autumn N addition might overestimate the negative effect of annual atmospheric N deposition on ecosystem stability,suggesting that to better evaluate the influence of N deposition in temperate grasslands,both field experiments and global modeling should consider not only the annual N load but also its seasonal dynamics.Moreover,further studies should pay more attention to the alteration in the ecosystem temporal deviations,which might be more sensitive to human-induced environmental changes.展开更多
This paper proposes the concept of generalized L systems, GL systems for short, which can describe asynchronized concurrent phenomena. We have proved that the GL systems are proper extensions of the traditional L syst...This paper proposes the concept of generalized L systems, GL systems for short, which can describe asynchronized concurrent phenomena. We have proved that the GL systems are proper extensions of the traditional L systems. We have also defined a classification of GL systems and proved a sufficient and necessary condition for the equivalence of two subclasses of GL systems: two GPDOL (a class of deterministic GL systems) systems L[ m1, m2, ??? mj] and L[ n1, n2, ??? nk] are e-quivalent, iff k = j and there exists a common divisor g of all mi and a common divisor h of all nj such that (?) i: mi/g = nj/h.展开更多
Atmospheric nitrogen (N) deposition includes inorganic N (IN) and organic N (ON).IN enrichment trends to reduce species richness greater than ON,likely lowering ecosystem stability,as species richness and ecosystem st...Atmospheric nitrogen (N) deposition includes inorganic N (IN) and organic N (ON).IN enrichment trends to reduce species richness greater than ON,likely lowering ecosystem stability,as species richness and ecosystem stability are usually positively related.However,previous field experiments evaluating N deposition effects on ecosystem stability used either IN or ON additions,likely biasing results.We assessed the effects of IN:ON ratios (0:10,3:7,5:5,7:3,and 10:0) at 10 g N m^(-2) year^(-1) on the temporal stability of plant community productivity in a temperate meadow grassland using 6-year (2017-2022) data from a long-term N addition experiment established in 2014.Species richness,species asynchrony,population stability,and dominant species stability were investigated to explore mechanisms underlying community stability changes.We found that IN:ON ratio showed no significant effect on community stability,although all N addition significantly reduced community stability (averaged 26.7% reduction).However,IN decreased species richness more than ON (54.1% reduction in 10:0 vs.31.8% reduction in 0:10).IN:ON ratio showed no significant effect on species asynchrony,population stability or dominant species stability.Species asynchrony and dominant species stability were both positively related to community stability,while population stability showed no significant association.It implies that species asynchrony and dominant species stability maintained community stability across IN:ON ratios.Overall,our findings suggest that,despite IN reducing species richness greater than ON,it may be reasonable to assess N deposition effects on ecosystem stability using either IN or ON addition.展开更多
文摘The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key technologies for ensuring the success of rocket flights and has been a core topic in carrier rocket technology research. The Gravity-1 solid carrier rocket is the first solid rocket bundled rocket developed by China, adopting a configuration with four boosters and a core stage bundled together. During the actual flight process, the four booster engines are ignited first, and then, in the event of insufficient control force from the boosters, the core stage engine is ignited to participate in control. To address thrust asynchrony during the descent of the four boosters, an Extended State Observer(ESO) is employed in the control scheme for this flight segment. This involves real-time estimation and compensation of attitude parameters during flight, identification of thrust asynchrony among the boosters, and simultaneous determination of whether the core stage engine is ignited to participate in control.Through six degrees of freedom simulation analysis and Y1 flight test validation, this method has been proven to be correct and feasible.
文摘In this paper, the asynchrony problem of distributed detection is analyzed and discussed.Two approaches are proposed and related results are given. It is shown that all fusion rules can beunified in the framework with asynchrony which could be much ciooer to industrial practice.
文摘Patient–ventilator asynchrony in Saudi Arabia practices is common,and more emphasis on how to mitigate such a clinical problem is needed.This letter is intended to shed the light on the current national evidence of patient–ventilator asynchrony and how to step ahead for better patients'ventilation management.
基金the National Natural Science Foundation of China(U20A2009,41991234,42077422 and 41725003)the National Key Research and Development Program of China(2022YFF1301801)the Major Science and Technology Projects in Tibet(XZ202101ZD0007G and XZ202101ZD0003N).
文摘Asymmetric seasonal warming,characterized by more pronounced temperature increases in winter than in summer,has become a critical feature of global warming,especially in cold and high-altitude regions.Previous studies have primarily focused on year-round warming,while comparatively less attention was paid to winter warming.However,a significant knowledge gap exists regarding the impacts of winter warming on ecosystem functions.To address this,we conducted an 8-year manipulated warming experiment in an alpine grassland on the Tibetan Plateau,employing three treatments:no warming,year-round warming and winter warming.We found that neither year-round warming nor winter warming significantly alters species richness at the community level.Notably,community biomass stability was maintained via species asynchrony.However,warming exerted significant effects on the plant abundance groups(dominant,common and rare species).Specifically,winter warming enhanced the stability of dominant species by increasing species asynchrony of dominant species,as the compensatory dynamics occurred between the grass and forbs.In contrast,year-round warming reduced the stability of common species,correlated with an increase in species richness and a decline in asynchrony among common species.Thus,our study underscores the capacity of alpine grassland to maintain community biomass stability via asynchrony dynamics of species under different warming conditions,although the stability of different abundance groups would be changed.Importantly,our results provide valuable insights for understanding the alpine grassland ecosystem on the Tibetan Plateau.
基金supported by the Key Research and Development and Transformation Plan of Qinghai Provincial Science and Technology Department(2024-NK-137)the Qinghai Province Science and Technology Commissioner Special Project(2024-NK-P28).
文摘In recent years,many studies have focused on the effects of global climate warming and increased nitrogen deposition on the structure and function of grassland ecosystem.However,there are still significant uncertainties in the response mechanism of stability of plant community biomass in alpine meadows of the Qinghai-Xizang Plateau,China to these two major climate factors.Given this,based on field control experiments,this study systematically evaluated the effects of different levels of climate warming(W0(no warming),W1(air temperature increased by 0.47℃ or soil temperature increased by 0.61℃),W2(air temperature increased by 0.92℃ or soil temperature increased by 1.09℃),W3(air temperature increased by 1.44℃ or soil temperature increased by 1.95℃)),nitrogen deposition(N0(0 kg N/(hm^(2)·a)),N16(16 kg N/(hm^(2)·a)),and N32(32 kg N/(hm^(2)·a))),and their interactions on plant community biomass and its temporal stability,and explored its potential regulatory mechanisms.The results showed that the biomass of total community,Gramineae,and dominant species increased significantly with increasing temperature,but the biomass of common and rare species decreased significantly.Nitrogen deposition also significantly promoted the biomass accumulation of community and gramineous plants.Under the treatment of W3N32,the biomass of plant community,Gramineae,and dominant species reached the highest values,indicating that there was a synergistic effect under this treatment.Structural equation model showed that increasing temperature significantly decreased the stability of plant community biomass by reducing the stability of grass and dominant species biomass and weakening species asynchronism.Interaction of increased nitrogen deposition and temperature increased the biomass fluctuation of grass functional group,thus amplifying its negative influence on community stability.More attention should be paid to the response and regulatory mechanisms of dominant species and functional groups under global climate change.This study provides a theoretical basis for revealing the stability maintenance mechanism of alpine grassland and also provides scientific support for the development of future grassland ecosystem management and assessment.
基金supported by the National Natural Science Foundation of China(Grant Nos.11003041 and 11203006)Shandong Provincial Natural Science Foundation(Grant Nos.ZR2009AM021,ZR2012AQ029,ZR2012AM008 and ZR2010AL025)+1 种基金Dezhou University Foundation(Grant No.402126)supported by Open Research Program of Key Laboratory for the Structure and Evolution of Celestial Objects,Chinese Academy of Sciences(Grant No.OP201102)
文摘In this paper, the relative phase relationship between flare index and sunspot activity （sunspot numbers and sunspot areas） is investigated. It is found that （i） the flare index and sunspot activity are asynchronous in phase space at all period scales, and the former lags behind the latter, which implies our results are supported for the integral response model; （ii） their different definitions and physical meanings may be a major reason for their phase asynchrony between them, and the solar flare activity favor to be related to the magnetic complex rather than magnetic strength.
基金supported by the National Natural Science Foundation of China(31670393)to L.Z.
文摘Host-mediated effects on hemiparasitic mistletoes were hypothesized to contribute to mistletoes reproductive phenological asynchrony,thus providing a longer period of food supply to its mutualistic pollinators and dispersers.However,studies with empirical data interrogating this hypothesis are lacking.Weekly monitoring of flowering and fruiting patterns on a generalist mistletoe Dendrophthoe pentandra(Loranthaceae)was conducted for two consecutive years in tropical Xishuangbanna,Southwest China.We examined whether flowering and fruiting patterns were seasonal,quantified the degree of stagger within D.pentandra populations and determined the factors influencing the first flowering date(FFD)of D.pentandra.Furthermore,the effect of change in the number of host species on reproductive phenological asynchrony of mistletoe was examined.We found that(i)both flowering and fruiting exhibited unimodal peaks in the two consecutive years of the study;(ii)the FFD was significantly influenced by crown area of mistletoe and light,such that clump with larger crown and more light exposure had an earlier FFD and longer flowering and fruiting durations;(iii)different host species had a significant impact on the phenology of mistletoes.However,contrary to our hypothesis,the number of host species did not significantly change the asynchrony of reproductive phenology of mistletoe.Therefore,these results suggest that alternative hypotheses are needed to interpret the ecological significance of the number of host species and phenological asynchrony of generalist mistletoes.
基金financially supported by the National Key Research and Development Program(2016YFC0502002)National Natural Science Foundation of China(41401072)+1 种基金the Science Foundation for Young Scientists of IMDE,CASthe Open Fund of the Key Laboratory of Mountain Surface Processes and Ecological Regulation,CAS
文摘The mechanism that sustains the temporal stability of aboveground net primary production(ANPP)respond to nitrogen deposition is still controversial.Consequently,we investigated the mechanism of temporal stability of ANPP through the effect of N addition on diversity,species asynchrony andportfolio effects in northern Tibet alpine steppe over a period of three years.Our results showed that the community temporal stability did not significantly correlate with the species richness and Shannon–Wiener diversity.Species asynchrony and stability was also not significantly affected by N addition(p>0.05).Furthermore,there was no significant relationship between species asynchrony and temporal stability.Although the value of portfolio effects(z)(z=1.304,95%confidence intervals:1.029–1.597)was more than 1,the portfolio effects was not a primary driver of temporal stability due to the biodiversity being unaffected.The above results suggested that the richness,species asynchrony and portfolio effect could not support for mechanism of stability at the alpine steppe.From the results of path analysis,species temporal stability positively supports the community temporal stability in the alpine steppe ecosystem.According to the character of environment and vegetation of alpine steppe at North Tibet,we inferred that dominance species stability is more important than species richness for the community temporal stability.
基金supported by Fundacāo Cearense de Apoio ao Desenvolvimento Científicoe Tecnológico (FUNCAP) (093.01.00/09)National Council for Scientific and Technological Development(CNPq),Brazil
文摘Deciduous trees with high-density wood that occur in dry seasonal tropical regions respond to rainfall seasonality with synchrony in phenophases. However, they may exhibit interannual differences in synchrony and intensity of phenophases, as strategy for large variations in duration and intensity of rainfall pulses. Nevertheless, it remains unknown how phenophases of deciduous trees of the Brazilian semi-arid region respond to rainfall variations. The phenology of Cordia oncocalyx was monitored in deciduous thorny woodland （Caatinga）, from April 2009 to March 2011, and was correlated with rainfall, soil humidity, temperature, and photoperiod. The rainy years 2009 and 2011 exhibited higher duration of rainfall pulses and lower frequency of interpulses, but in 2010 pulse duration and total rainfall were lower. Circular statistics showed leaf flush followed by flowering and fruiting in the rainy season, and leaf fall and seed dispersal in the dry season.
基金supported by Agriculture and Food Research Initiative Competitive Grant 2013-67013-21105 from the U.S. Department of Agriculture National Institute of Food to YWthe National Natural Science Foundation of China to YH (No. 31271350)
文摘Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sativus, 2n = 2x = 14) and its relative C. hystrix(2n = 2x = 24) followed by chemical induction of chromosome doubling. The resulting allotetraploid plant was self-pollinated for three generations. The fertility and seed set of the amphidiploid plants were very low. In this study, we investigated the meiotic chromosome behavior in pollen mother cells with the aid of fluorescence in situ hybridization, aiming to identify the reasons for the low fertility and seed set in the amphidiploid plants. Homologous chromosome pairing appeared normal, but chromosome laggards were common, owing primarily to asynchronous meiosis of chromosomes from the two donor genomes. We suggest that asynchronous meiotic rhythm between the two parental genomes is the main reason for the low fertility and low seed set of the C. hystrix–cucumber amphidiploid plants.
文摘Inbreeding negatively affects various life-history traits, with inbred individuals typically having lower fit- ness than outbred individuals （=inbreeding depression）. Inbreeding depression is often emphasized under environmental stress, but the underlying mechanisms and potential long-lasting consequences of such inbreeding-environment interactions remain poorly understood. Here, we hypothesize that inbreeding-environment interactions that occur early in life have long-term physiological effects, in partic- ular on the adult oxidative balance. We applied a unique experimental design to manipulate early life conditions of inbred and outbred songbirds （Serinus canaria） that allowed us to separate prenatal and postnatal components of early life conditions and their respective importance in inbreeding-environment interactions. We measured a wide variety of markers of oxidative status in adulthood, resulting in a com- prehensive account for oxidative balance. Using a Bayesian approach with Markov chain Monte Carlo, we found clear sex-specific effects and we also found only in females small yet significant long-term effects of inbreeding-environment interactions on adult oxidative balance. Postnatal components of early life conditions were most persuasively reflected on adult oxidative balance, with inbred females that experienced disadvantageous postnatal conditions upregulating enzymatic antioxidants in adulthood. Our study provides some evidence that adult oxidative balance can reflect inbreeding-environment inter- actions early in life, but given the rather small effects that were limited to females, we conclude that oxida- tive stress miaht have a limited role as mechanism underlvina inhre.e.dina-envirnnme.nt inte.raetinn.q_
基金supported by the Spanish Ministerio de CienciaInnovación y Universidades and European(FEDER)Funds(CGL2017-83103-P)。
文摘Sibling cannibalism is relatively common in nature,but its evolution in birds and certain other vertebrates with extended parental care had been discarded.Here,however,we demonstrate its regular occurrence in two European populations of the Eurasian hoopoe(Upupa epops)and explore possible adaptive and non-adaptive explanations.Results showed that sibling cannibalism was more frequently detected in Spain(51.7%)than in Austria(5.9%).In these two populations,the hoopoes laid similar clutch sizes,resulting in similar fledging production,but hatching failures were more frequent in the northern population.Consequently,having more nestlings condemned to die in the southern population may explain the higher incidence of sibling cannibalism.In accordance with this interpretation,hatching span and failure,but not breeding date,explained the probability of sibling cannibalism in the Spanish hoopoes,while all three variables predicted brood reduction intensity.Furthermore,experimental food supply reduced the probability of sibling cannibalism,but not the intensity of brood reduction.Finally,females allocated fewer resources to the smallest nestlings when they were going to starve,but not necessarily when they were going to be used as food for their siblings.These results suggest that hoopoes produce extra eggs that,in the case of reduced hatching failure and food scarcity,produce nestlings that are used to feed older siblings.These findings provide the first evidence that sibling cannibalism occurs regularly in a bird species,thus expanding our evolutionary understanding of clutch size,hatching asynchrony,parent-offspring conflict,infanticide,and sibling cannibalism in the animal kingdom.
基金supported by the National Natural Science Foundation of China(Grant No.U24A20199)the Major Science and Technology Projects in Jiangsu Province(Grant No.BG2024038)the Youth Foundation of Jiangsu Province(Grant No.BK20241421)。
文摘This paper proposes a hierarchical dual-horizon preview control strategy for semi-active suspensions with CDC dampers and dual-chamber air springs.To address the preview information uncertainties and actuator delay,the upper layer employs a tube-based model predictive controller using long-horizon preview information,while the lower layer uses shorthorizon preview with a GRNN-based delay model to adjust the preview window in real time.A frequency-domain force separation approach is introduced to synchronize the actuator response.Experimental results show up to 50.49% improvement in suspension force tracking under Class-C road conditions,validating the effectiveness of the proposed method in enhancing ride comfort and actuator coordination under uncertainty.
基金funding from the National Natural Science Foundation of China(Grant Nos.62375078 and 12002197)the Youth Talent Launching Program of Shanghai University+2 种基金the General Science Foundation of Henan Province(Grant No.222300420427)the Key Research Project Plan for Higher Education Institutions in Henan Province(Grant No.24ZX011)the National Key Laboratory of Ship Structural Safety
文摘Three-dimensional(3D)imaging with structured light is crucial in diverse scenarios,ranging from intelligent manufacturing and medicine to entertainment.However,current structured light methods rely on projector-camera synchronization,limiting the use of affordable imaging devices and their consumer applications.In this work,we introduce an asynchronous structured light imaging approach based on generative deep neural networks to relax the synchronization constraint,accomplishing the challenges of fringe pattern aliasing,without relying on any a priori constraint of the projection system.To overcome this need,we propose a generative deep neural network with U-Net-like encoder-decoder architecture to learn the underlying fringe features directly by exploring the intrinsic prior principles in the fringe pattern aliasing.We train within an adversarial learning framework and supervise the network training via a statisticsinformed loss function.We demonstrate that by evaluating the performance on fields of intensity,phase,and 3D reconstruction.It is shown that the trained network can separate aliased fringe patterns for producing comparable results with the synchronous one:the absolute error is no greater than 8μm,and the standard deviation does not exceed 3μm.Evaluation results on multiple objects and pattern types show it could be generalized for any asynchronous structured light scene.
基金supported by grants from the National Natural Science Foundation of China(31630010 and 31320103916).
文摘Aims Long-term heavy grazing reduces plant diversity and ecosystem function by intensifying nitrogen(N)and water limitation.In contrast,the absence of biomass removal can cause species loss by elevating light competition and weakening community stability,which is exacerbated by N and water enrichment.Hence,how to maintain species diversity and community stability is still a huge challenge for sustainable management of worldwide grasslands.Methods We conducted a 4-year manipulated experiment in six long-term grazing blocks to explore combination of resource additions and biomass removal(increased water,N and light availability)on species richness and community stability in semiarid grasslands of Inner Mongolia,China.Important Findings In all blocks treated with the combination of resource additions and biomass removal,primary productivity increased and species richness and community stability were maintained over 4 years of experiment.At both species and plant functional group(PFG)levels,the aboveground biomass of treated plants remained temporally stable in treatments with the combination of N and/or water addition and biomass removal.The maintenance of species richness was primarily caused by the biomass removal,which could increase the amount of light exposure for grasses under resource enrichment.Both species asynchrony and stability of PFGs contributed to the high temporal stability observed in these communities.Our results indicate that management practices of combined resource enrichment with biomass removal,such as grazing or mowing,could not only enhance primary productivity but also maintain plant species diversity,species asynchrony and community stability.Furthermore,as overgrazing-induced degradation and resource enrichment-induced biodiversity loss continue to be major problems worldwide,our findings have important implications for adaptive management in semiarid grasslands and beyond.
基金supported by the National Natural Science Foundation of China(32060284,31870441)the Natural Science Foundation of Inner Mongolia,China(2019JQ04)+2 种基金the Central Government Guides the Local Science and Technology Development Foundation(2020ZY0027)the National Science Foundation of the United States(DEB-1856318,CBET-1833988)the Natural Science Foundation of Hebei Province(C2022201042)。
文摘Nitrogen enrichment and land use are known to influence various ecosystems,but how these anthropogenic changes influence community and ecosystem responses to disturbance remains poorly understood.Here we investigated the effects of increased nitrogen input and mowing on the resistance and recovery of temperate semiarid grassland experiencing a three-year drought.Nitrogen addition increased grassland biomass recovery but decreased structural recovery after drought,whereas annual mowing increased grassland biomass recovery and structural recovery but reduced structural resistance to drought.The treatment effects on community biomass/structural resistance and recovery were largely modulated by the stability of the dominant species and asynchronous dynamics among species,and the community biomass resistance and recovery were also greatly driven by the stability of grasses.Community biomass resistance/recovery in response to drought was positively associated with its corresponding structural stability.Our study provides important experimental evidence that both nitrogen addition and mowing could substantially change grassland stability in both functional and structural aspects.Our findings emphasize the need to study changes across levels of ecological organization for a more complete understanding of ecosystem responses to disturbances under widespread environmental changes.
基金Supported by the National Natural Science Foundation of China(No.11671142 and 11371087)STCSM(No.13dz2260400)Shanghai Leading Academic Discipline Pro ject(No.B407)
文摘In this paper we devote ourselves to the study of the asymptotic behavior of a size-structured pop- ulation dynamics with random diffusion and delayed birth process. Within a semigroup framework, we discuss the local stability and asynchrony respectively for the considered population system under some conditions. We use for our discussion the techniques of operator matrices, Hille-Yosida operators, positivity, spectral analysis as well as Perron-Frobenius theory.
基金funded by the National Natural Science Foundation of China (32122055 and 32071603)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA26020101).
文摘Nitrogen(N)deposition decreases the temporal stability of ecosystem aboveground biomass production(ecosystem stability).However,little is known about how the responses of ecosystem stability differ based on seasonal N enrichment.By adding N in autumn,winter,or growing season,from October 2014 to May 2020,in a temperate grassland in northern China,we found that only N addition in autumn resulted in a significantly positive correlation between ecosystem mean aboveground net primary productivity(ANPP)and its standard deviation and significantly reduced ecosystem stability.Autumn N-induced reduction in ecosystem stability was associated with the vanished negative effect of community-wide species asynchrony(asynchronous dynamics among populations to environmental perturbations)on the standard deviation of ecosystem ANPP in combination with the emerged positive effect of dominance(Simpson's dominance index that indicates the relative weight of dominant species in a community).Our findings indicate that autumn N addition might overestimate the negative effect of annual atmospheric N deposition on ecosystem stability,suggesting that to better evaluate the influence of N deposition in temperate grasslands,both field experiments and global modeling should consider not only the annual N load but also its seasonal dynamics.Moreover,further studies should pay more attention to the alteration in the ecosystem temporal deviations,which might be more sensitive to human-induced environmental changes.
基金This work was partially supported by Pre-973 Project 2001 CCA03000, the National Natural ScienceFoundation of China (Grant No. 69733020) Brain and Mind Foundation of the Chinese Academy of Sciences, Innovation Foundation of AMSS, IOM and ICT.
文摘This paper proposes the concept of generalized L systems, GL systems for short, which can describe asynchronized concurrent phenomena. We have proved that the GL systems are proper extensions of the traditional L systems. We have also defined a classification of GL systems and proved a sufficient and necessary condition for the equivalence of two subclasses of GL systems: two GPDOL (a class of deterministic GL systems) systems L[ m1, m2, ??? mj] and L[ n1, n2, ??? nk] are e-quivalent, iff k = j and there exists a common divisor g of all mi and a common divisor h of all nj such that (?) i: mi/g = nj/h.
基金National Key Research and Development Program of China (2022YFF1300603, 2022YFE0128000)the National Natural Science Foundation of China (32171592, 32061123005, 31270476)Scientific and Technological Innovation Project of China Academy of Chinese Medical Sciences (CI2024C003YN)。
文摘Atmospheric nitrogen (N) deposition includes inorganic N (IN) and organic N (ON).IN enrichment trends to reduce species richness greater than ON,likely lowering ecosystem stability,as species richness and ecosystem stability are usually positively related.However,previous field experiments evaluating N deposition effects on ecosystem stability used either IN or ON additions,likely biasing results.We assessed the effects of IN:ON ratios (0:10,3:7,5:5,7:3,and 10:0) at 10 g N m^(-2) year^(-1) on the temporal stability of plant community productivity in a temperate meadow grassland using 6-year (2017-2022) data from a long-term N addition experiment established in 2014.Species richness,species asynchrony,population stability,and dominant species stability were investigated to explore mechanisms underlying community stability changes.We found that IN:ON ratio showed no significant effect on community stability,although all N addition significantly reduced community stability (averaged 26.7% reduction).However,IN decreased species richness more than ON (54.1% reduction in 10:0 vs.31.8% reduction in 0:10).IN:ON ratio showed no significant effect on species asynchrony,population stability or dominant species stability.Species asynchrony and dominant species stability were both positively related to community stability,while population stability showed no significant association.It implies that species asynchrony and dominant species stability maintained community stability across IN:ON ratios.Overall,our findings suggest that,despite IN reducing species richness greater than ON,it may be reasonable to assess N deposition effects on ecosystem stability using either IN or ON addition.
