Multiplicative noise removal problems have attracted much attention in recent years.Unlike additive noise,multiplicative noise destroys almost all information of the original image,especially for texture images.Motiva...Multiplicative noise removal problems have attracted much attention in recent years.Unlike additive noise,multiplicative noise destroys almost all information of the original image,especially for texture images.Motivated by the TV-Stokes model,we propose a new two-step variational model to denoise the texture images corrupted by multiplicative noise with a good geometry explanation in this paper.In the first step,we convert the multiplicative denoising problem into an additive one by the logarithm transform and propagate the isophote directions in the tangential field smoothing.Once the isophote directions are constructed,an image is restored to fit the constructed directions in the second step.The existence and uniqueness of the solution to the variational problems are proved.In these two steps,we use the gradient descent method and construct finite difference schemes to solve the problems.Especially,the augmented Lagrangian method and the fast Fourier transform are adopted to accelerate the calculation.Experimental results show that the proposed model can remove the multiplicative noise efficiently and protect the texture well.展开更多
Background Domestic goose breeds are descended from either the Swan goose(Anser cygnoides)or the Greylag goose(Anser anser),exhibiting variations in body size,reproductive performance,egg production,feather color,and ...Background Domestic goose breeds are descended from either the Swan goose(Anser cygnoides)or the Greylag goose(Anser anser),exhibiting variations in body size,reproductive performance,egg production,feather color,and other phenotypic traits.Constructing a pan-genome facilitates a thorough identification of genetic variations,thereby deepening our comprehension of the molecular mechanisms underlying genetic diversity and phenotypic variability.Results To comprehensively facilitate population genomic and pan-genomic analyses in geese,we embarked on the task of 659 geese whole genome resequencing data and compiling a database of 155 RNA-seq samples.By constructing the pan-genome for geese,we generated non-reference contigs totaling 612 Mb,unveiling a collection of 2,813 novel genes and pinpointing 15,567 core genes,1,324 softcore genes,2,734 shell genes,and 878 cloud genes in goose genomes.Furthermore,we detected an 81.97 Mb genomic region showing signs of genome selection,encompassing the TGFBR2 gene correlated with variations in body weight among geese.Genome-wide association studies utilizing single nucleotide polymorphisms(SNPs)and presence-absence variation revealed significant genomic associations with various goose meat quality,reproductive,and body composition traits.For instance,a gene encoding the SVEP1 protein was linked to carcass oblique length,and a distinct gene-CDS haplotype of the SVEP1 gene exhibited an association with carcass oblique length.Notably,the pan-genome analysis revealed enrichment of variable genes in the“hair follicle maturation”Gene Ontology term,potentially linked to the selection of feather-related traits in geese.A gene presence-absence variation analysis suggested a reduced frequency of genes associated with“regulation of heart contraction”in domesticated geese compared to their wild counterparts.Our study provided novel insights into gene expression features and functions by integrating gene expression patterns across multiple organs and tissues in geese and analyzing population variation.Conclusion This accomplishment originates from the discernment of a multitude of selection signals and candidate genes associated with a wide array of traits,thereby markedly enhancing our understanding of the processes underlying domestication and breeding in geese.Moreover,assembling the pan-genome for geese has yielded a comprehensive apprehension of the goose genome,establishing it as an indispensable asset poised to offer innovative viewpoints and make substantial contributions to future geese breeding initiatives.展开更多
Variations of picoplankton groups were investigated over a one-month period in Daya Bay and Sanya Bay,in the northern South China Sea.The two coastal regions exhibited different variation patterns in physicochemical p...Variations of picoplankton groups were investigated over a one-month period in Daya Bay and Sanya Bay,in the northern South China Sea.The two coastal regions exhibited different variation patterns in physicochemical parameters.Moreover,the diel variations of picoplankton groups were different between the two bays.The abundance of the picoplankton in Sanya Bay displayed a pronounced diel variation,while it was not significant in Daya Bay.In addition,some similar patterns of picoplankton abundance were discovered.In the two bays,virioplankton exhibited the smallest fluctuation range,whereas picocyanobacteria fluctuated most markedly.The fluctuation range of picoplankton groups was larger in spring tide than in neap tide,especially in Sanya Bay.Random forest model analysis demonstrated that the variation of picoplankton groups was attributed to physical and chemical factors in Sanya Bay and Daya Bay,respectively.Therefore,our findings suggest that virioplankton abundance can persist more stably in response to changing environmental conditions compared to bacterioplankton and picophytoplankton.展开更多
Plankton are an important component of marine protected areas(MPAs),and its communities would require much smaller interpatch distances to ensure connection among MPAs.According to the survey from MPAs dominated by ar...Plankton are an important component of marine protected areas(MPAs),and its communities would require much smaller interpatch distances to ensure connection among MPAs.According to the survey from MPAs dominated by artificial reefs and adjacent waters(estuary area(EA),aquaculture area(AA),artificial reef area(ARA),natural area(NA)and comprehensive effect area(CEA))in Haizhou Bay in spring and autumn,we analyzed phyto-zooplankton composition,abundance and biomass,and correlation with hydrologic variables to gain information about the forces that structure the plankton.The results showed that the dominant zooplankton were copepods(spring,98.9%;autumn,94.2%),while the phytoplankton were mainly composed of Bacillariophyta(spring,61.8%;autumn,95.6%).The RDA results showed that temperature,salinity and depth highly associated with the distribution and composition of plankton species among the habitats than other factors in spring;temperature,Chla and DO had the strongest influence in autumn.The zooplankton in the ARA and AA ecosystems basically contained the same species as those in other habitats,and each habitat also exhibited a relatively unique combination of plankton species.The structures of the EA zooplankton in spring and the EA phytoplankton in both seasons were much different than other habitats,which may have been caused by factors such as currents and tides.We concluded that there exists similarity of the plankton community between artificial reef area and adjacent waters,whereas the EAs may be relatively independent systems.Therefore,these interaction between plankton community should be considered when designing MPA networks,and ocean circulations should be considered more than the environmental factors.展开更多
Seed size is an important agronomic trait in melons that directly affects seed germination and subsequent seedling growth.However,the genetic mechanism underlying seed size in melon remains unclear.In the present stud...Seed size is an important agronomic trait in melons that directly affects seed germination and subsequent seedling growth.However,the genetic mechanism underlying seed size in melon remains unclear.In the present study,we employed Bulked-Segregant Analysis sequencing(BSA-seq)to identify a candidate region(~1.35 Mb)on chromosome 6 that corresponds to seed size.This interval was confirmed by QTL mapping of three seed size-related traits from an F2 population across three environments.This mapping region represented nine QTLs that shared an overlapping region on chromosome 6,collectively referred to as qSS6.1.New InDel markers were developed in the qSS6.1 region,narrowing it down to a 68.35 kb interval that contains eight annotated genes.Sequence variation analysis of the eight genes identified a SNP with a C to T transition mutation in the promoter region of MELO3C014002,a leucine-rich repeat receptor-like kinase(LRR-RLK)gene.This mutation affected the promoter activity of the MELO3C014002 gene and was successfully used to differentiate the large-seeded accessions(C-allele)from the small-seeded accessions(T-allele).qRT-PCR revealed differential expression of MELO3C014002 between the two parental lines.Its predicted protein has typical LRR-RLK family domains,and phylogenetic analyses reveled its similarity with the homologs in several plant species.Altogether,these findings suggest MELO3C014002 as the most likely candidate gene involved in melon seed size regulation.Our results will be helpful for better understanding the genetic mechanism regulating seed size in melons and for genetically improving this important trait through molecular breeding pathways.展开更多
Macrophyte habitats exhibit remarkable heterogeneity,encompassing the spatial variation of abiotic and biotic components such as changes in water conditions and weather as well as anthropogenic stressors.Environmental...Macrophyte habitats exhibit remarkable heterogeneity,encompassing the spatial variation of abiotic and biotic components such as changes in water conditions and weather as well as anthropogenic stressors.Environmental factors are thought to be important drivers shaping the genetic and epigenetic variation of aquatic plants.However,the links among genetic diversity,epigenetic variation,and environmental variables remain largely unclear,especially for clonal aquatic plants.Here,we performed population genetic and epigenetic analyses in conjunction with habitat discrimination to elucidate the environmental factors driving intraspecies genetic and epigenetic variation in hornwort(Ceratophyllum demersum)in a subtropical lake.Environmental factors were highly correlated with the genetic and epigenetic variation of C.demersum,with temperature being a key driver of the genetic variation.Lower temperature was detected to be correlated with greater genetic and epigenetic variation.Genetic and epigenetic variation were positively driven by water temperature,but were negatively affected by ambient air temperature.These findings indicate that the genetic and epigenetic variation of this clonal aquatic herb is not related to the geographic feature but is instead driven by environmental conditions,and demonstrate the effects of temperature on local genetic and epigenetic variation in aquatic systems.展开更多
Besides the rapid retreating trend of Arctic sea-ice extent(SIE),this study found the most outstanding low-frequency variation of SIE to be a 4-6-year periodic variation.Using a clustering analysis algorithm,the SIE i...Besides the rapid retreating trend of Arctic sea-ice extent(SIE),this study found the most outstanding low-frequency variation of SIE to be a 4-6-year periodic variation.Using a clustering analysis algorithm,the SIE in most ice-covered regions was clustered into two special regions:Region-1 around the Barents Sea and Region-2 around the Canadian Basin,which were located on either side of the Arctic Transpolar Drift.Clear 4-6-year periodic variation in these two regions was identified using a novel method called“running linear fitting algorithm”.The rate of temporal variation of the Arctic SIE was related to three driving factors:the regional air temperature,the sea-ice areal flux across the Arctic Transpolar Drift,and the divergence of sea-ice drift.The 4-6-year periodic variation was found to have always been present since 1979,but the SIE responded to different factors under heavy and light ice conditions divided by the year 2005.The joint contribution of the three factors to SIE variation exceeded 83%and 59%in the two regions,respectively,remarkably reflecting their dynamic mechanism.It is proven that the process of El Niño-Southern Oscillation(ENSO)is closely associated with the three factors,being the fundamental source of the 4-6-year periodic variations of Arctic SIE.展开更多
Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population dynamics.Despite numerous studies on this subject in north-temperate environ...Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population dynamics.Despite numerous studies on this subject in north-temperate environments,there is a lack of equivalent studies at similar latitudes in the south.Here,we used a 14-year dataset of capture,banding,and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens(Troglodytes aedon bonariae).We evaluated temporal variation in sur-vival and the effect of environmental(climatic)and demographic variables(adult abundance,total number of fledglings produced during each breeding season)on survival estimators.We found that the probability of adult survival decreased as the abundance of breeding adults increased.This density-dependent effect could be related to the resident lifestyle of southern House Wrens,which could determine an intense competition for territories and resources that ultimately would affect their survival.展开更多
El Ni?o–Southern Oscillation(ENSO) exhibits a distinctive phase-locking characteristic, first expressed during its onset in boreal spring, developing during summer and autumn, reaching its peak towards winter, and de...El Ni?o–Southern Oscillation(ENSO) exhibits a distinctive phase-locking characteristic, first expressed during its onset in boreal spring, developing during summer and autumn, reaching its peak towards winter, and decaying over the next spring. Several studies have demonstrated that this feature arises as a result of seasonal variation in the growth rate of ENSO as expressed by the sea surface temperature(SST). The bias towards simulating the phase locking of ENSO by many state-of-the-art climate models is also attributed to the unrealistic depiction of the growth rate. In this study, the seasonal variation of SST growth rate in the Ni?o-3.4 region(5°S–5°N, 120°–170°W) is estimated in detail based on the mixed layer heat budget equation and recharge oscillator model during 1981–2020. It is suggested that the consideration of a variable mixed layer depth is essential to its diagnostic process. The estimated growth rate has a remarkable seasonal cycle with minimum rates occurring in spring and maximum rates evident in autumn. More specifically, the growth rate derived from the meridional advection(surface heat flux) is positive(negative) throughout the year. Vertical diffusion generally makes a negative contribution to the evolution of growth rate and the magnitude of vertical entrainment represents the smallest contributor. Analysis indicates that the zonal advective feedback is regulated by the meridional immigration of the intertropical convergence zone, which approaches its southernmost extent in February and progresses to its northernmost location in September, and dominates the seasonal variation of the SST growth rate.展开更多
A complete road-soft ground model is established in this paper to study the dynamic responses caused by vehicle loads and/or daily temperature variation.A dynamic thermo-elastic model is applied to capturing the behav...A complete road-soft ground model is established in this paper to study the dynamic responses caused by vehicle loads and/or daily temperature variation.A dynamic thermo-elastic model is applied to capturing the behavior of the rigid pavement,the base course,and the subgrade,while the soft ground is characterized using a dynamic thermo-poroelastic model.Solutions to the road-soft ground system are derived in the Laplace-Hankel transform domain.The time domain solutions are obtained using an integration approach.The temperature,thermal stress,pore water pressure,and displacement responses caused by the vehicle load and the daily temperature variation are presented.Results show that obvious temperature change mainly exists within 0.3 m of the road when subjected to the daily temperature variation,whereas the stress responses can still be found in deeper places because of the thermal swelling/shrinkage deformation within the upper road structures.Moreover,it is important to consider the coupling effects of the vehicle load and the daily temperature variation when calculating the dynamic responses inside the road-soft ground system.展开更多
Seed vigor is a crucial trait for the direct seeding of rice.Here we examined the genetic regulation of seed vigor traits in rice,including germination index(GI)and germination potential(GP),using a genome-wide associ...Seed vigor is a crucial trait for the direct seeding of rice.Here we examined the genetic regulation of seed vigor traits in rice,including germination index(GI)and germination potential(GP),using a genome-wide association study approach.One major quantitative trait locus,qGI6/qGP6,was identified simultaneously for both GI and GP.The candidate gene encoding the cytochrome c oxidase subunit 5B(OsCOX5B)was validated for qGI6/qGP6.The disruption of OsCOX5B caused the vigor traits to be significantly lower in Oscox5b mutants than in the japonica Nipponbare wild type(WT).Gene co-expression analysis revealed that OsCOX5B influences seed vigor mainly by modulating the tricarboxylic acid cycle process.The glucose levels were significantly higher while the pyruvic acid and adenosine triphosphate levels were significantly lower in Oscox5b mutants than in WT during seed germination.The elite haplotype of OsCOX5B facilitates seed vigor by increasing its expression during seed germination.Thus,we propose that OsCOX5B is a potential target for the breeding of rice varieties with enhanced seed vigor for direct seeding.展开更多
Mesoscale eddies are a prominent oceanic phenomenon that plays an important role in oceanic mass transport and energy conversion.Characterizing by rotational speed,the eddy intensity is one of the most fundamental pro...Mesoscale eddies are a prominent oceanic phenomenon that plays an important role in oceanic mass transport and energy conversion.Characterizing by rotational speed,the eddy intensity is one of the most fundamental properties of an eddy.However,the seasonal spatiotemporal variation in eddy intensity has not been examined from a global ocean perspective.In this study,we unveil the seasonal spatiotemporal characteristics of eddy intensity in the global ocean by using the latest satellite-altimetry-derived eddy trajectory data set.The results suggest that the eddy intensity has a distinct seasonal variation,reaching a peak in spring while attaining a minimum in autumn in the Northern Hemisphere and the opposite in the Southern Hemisphere.The seasonal variation of eddy intensity is more intense in the tropical-subtropical transition zones within latitudinal bands between 15°and 30°in the western Pacific Ocean,the northwestern Atlantic Ocean,and the eastern Indian Ocean because baroclinic instability in these areas changes sharply.Further analysis found that the seasonal variation of baroclinic instability precedes the eddy intensity by a phase of 2–3 months due to the initial perturbations needing time to grow into mesoscale eddies.展开更多
As an essential crop that provides vegetable oil and protein,soybean(Glycine max(L.)Merr.)is widely planted all over the world.However,the scarcity of water resources worldwide has seriously impacted on the quality an...As an essential crop that provides vegetable oil and protein,soybean(Glycine max(L.)Merr.)is widely planted all over the world.However,the scarcity of water resources worldwide has seriously impacted on the quality and yield of soybean.To address this,exploring excellent genes for improving drought resistance in soybean is crucial.In this study,we identified natural variations of GmFNSII-2(flavone synthase II)significantly affect the drought resistance of soybeans.Through sequence analysis of GmFNSII-2 in 632 cultivated and 44 wild soybeans nine haplotypes were identified.The full-length allele GmFNSII-2^(C),but not the truncated allele GmFNSII-2^(A) possessing a nonsense nucleotide variation,increased enzyme activity.Further research found that GmDREB3,known to increase soybean drought resistance,bound to the promoter region of GmFNSII-2^(C).GmDREB3 positively regulated the expression of GmFNSII-2^(C),increased flavone synthase abundance and improved the drought resistance.Furthermore,a singlebase mutation in the GmFNSII-2^(C) promoter generated an additional drought response element(CCCCT),which had stronger interaction strength with GmDREB3 and increased its transcriptional activity under drought conditions.The frequency of drought-resistant soybean varieties with Hap 1(Pro:GmFNSII-2^(C))has increased,suggesting that this haplotype may be selected during soybean breeding.In summary,GmFNSII-2^(C) could be used for molecular breeding of drought-tolerant soybean.展开更多
"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic s..."Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.展开更多
Reducing the process variation is a significant concern for resistive random access memory(RRAM).Due to its ultrahigh integration density,RRAM arrays are prone to lithographic variation during the lithography process,...Reducing the process variation is a significant concern for resistive random access memory(RRAM).Due to its ultrahigh integration density,RRAM arrays are prone to lithographic variation during the lithography process,introducing electrical variation among different RRAM devices.In this work,an optical physical verification methodology for the RRAM array is developed,and the effects of different layout parameters on important electrical characteristics are systematically investigated.The results indicate that the RRAM devices can be categorized into three clusters according to their locations and lithography environments.The read resistance is more sensitive to the locations in the array(~30%)than SET/RESET voltage(<10%).The increase in the RRAM device length and the application of the optical proximity correction technique can help to reduce the variation to less than 10%,whereas it reduces RRAM read resistance by 4×,resulting in a higher power and area consumption.As such,we provide design guidelines to minimize the electrical variation of RRAM arrays due to the lithography process.展开更多
Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combinat...Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass.The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method.The numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in advance.The results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.展开更多
The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the...The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the dynamic parameters of the ISWs in the northern South China Sea(SCS)were studied based on the reanalysis of long-term temperature and salinity datasets.The results for spectrum analysis show that there are definite geographical differences for the periodic variation of the parameters:in shallow water,all parameters vary with a wave period of one year,while in deep water wave components of the parameters at other frequencies exist.Using wavelet analysis,the wavelet power spectral densities in deep water exhibited an inter-annual variation pattern.For example,the wave component of the dispersion coefficient with a wave period of about half a year reached its power peak once every two years.Based on previous work,this inter-annual variation pattern was deduced to be caused by dynamic processes.In further work on the regulatory mechanisms,empirical orthogonal function(EOF)decomposition was performed.It was found that the modes of the dispersion coefficient have different geographical distributions,explaining the reason why the wave components in different frequencies appeared in different locations.The numerical simulation results confirm that the variations in the parameters of the ISWs derived from the eKdV equation could affect the waveforms significantly because of changes in the polarity of the ISWs.Therefore,the periodic variations of the dynamic parameters are related to the geographical location because of dynamic processes operating.展开更多
Flower constancy describes the phenomenon that pollinators tend to successively visit flowers of a single species during foraging,reducing reproductive interference in natural communities.The extent of flower constanc...Flower constancy describes the phenomenon that pollinators tend to successively visit flowers of a single species during foraging,reducing reproductive interference in natural communities.The extent of flower constancy is largely determined by the floral traits of co-flowering species.Both higher inter-specific and lower intraspecific differences of floral traits should contribute to a higher level of flower constancy.However,previous studies mainly focused on interspecific difference,and the intraspecific variation(consistency)of floral traits received much less attention.We hypothesise that selection may favour lower intraspecific floral trait variation in communities composed of multiple co-flowering congeners.We investigated the floral colour variation of three focal Pedicularis species that share pollinators in 19communities composed of either single or multiple Pedicularis species.Colour was quantified using image-based colour analysis as perceived by pollinators.We found that most of the intrapopulation floral colour variation was below the colour discrimination threshold of bumblebees,implying strongly constrained by the visual selection by pollinators.Contrary to the hypothesis,there is no significant difference in intraspecific floral colour variation between different community contexts.It may be due to the relatively large interspecific floral colour differences of most co-flowering species.The influence of community context on intraspecific variation may be reflected in floral traits other than colours.展开更多
Arctic sea ice is broadly regarded as an indicator and amplifier of global climate change.The rapid changes in Arctic sea ice have been widely concerned.However,the spatiotemporal changes in the horizontal and vertica...Arctic sea ice is broadly regarded as an indicator and amplifier of global climate change.The rapid changes in Arctic sea ice have been widely concerned.However,the spatiotemporal changes in the horizontal and vertical dimensions of Arctic sea ice and its asymmetry during the melt and freeze seasons are rarely quantified simultaneously based on multiple sources of the same long time series.In this study,the spatiotemporal variation and freeze-thaw asymmetry of Arctic sea ice were investigated from both the horizontal and vertical dimensions during 1979–2020 based on remote sensing and assimilation data.The results indicated that Arctic sea ice was declining at a remarkably high rate of–5.4×10^(4) km^(2)/a in sea ice area(SIA)and–2.2 cm/a in sea ice thickness(SIT)during 1979 to 2020,and the reduction of SIA and SIT was the largest in summer and the smallest in winter.Spatially,compared with other sub-regions,SIA showed a sharper declining trend in the Barents Sea,Kara Sea,and East Siberian Sea,while SIT presented a larger downward trend in the northern Canadian Archipelago,northern Greenland,and the East Siberian Sea.Regarding to the seasonal trend of sea ice on sub-region scale,the reduction rate of SIA exhibited an apparent spatial heterogeneity among seasons,especially in summer and winter,i.e.,the sub-regions linked to the open ocean exhibited a higher decline rate in winter;however,the other sub-regions blocked by the coastlines presented a greater decline rate in summer.For SIT,the sub-regions such as the Beaufort Sea,East Siberian Sea,Chukchi Sea,Central Arctic,and Canadian Archipelago always showed a higher downward rate in all seasons.Furthermore,a striking freeze-thaw asymmetry of Arctic sea ice was also detected.Comparing sea ice changes in different dimensions,sea ice over most regions in the Arctic showed an early retreat and rapid advance in the horizontal dimension but late melting and gradual freezing in the vertical dimension.The amount of sea ice melting and freezing was disequilibrium in the Arctic during the considered period,and the rate of sea ice melting was 0.3×10^(4) km^(2)/a and 0.01 cm/a higher than that of freezing in the horizontal and vertical dimensions,respectively.Moreover,there were notable shifts in the melting and freezing of Arctic sea ice in 1997/2003 and 2000/2004,respectively,in the horizontal/vertical dimension.展开更多
Seasonal variation of hearing sensitivity has been observed in many vertebrate groups with obvious vocal behaviors.Circulating hormones,conspecific calling signals,and temperature are potential factors that drive thes...Seasonal variation of hearing sensitivity has been observed in many vertebrate groups with obvious vocal behaviors.Circulating hormones,conspecific calling signals,and temperature are potential factors that drive these plasticity patterns.Turtles have a hearing range that appears to be limited to under 1.5 kHz and are often thought to be non-vocal;thus,they are commonly neglected in vocal communication research.In this study,we aimed to determine whether the auditory phenotype exhibits seasonal variation in sensitivity and to analyze the potential factors driving such variation patterns in turtles.We measured hearing sensitivity and sex hormone levels in female(estradiol)and male(testosterone and dihydrotestosterone)Red-eared sliders(Trachemys scripta elegans)during spring and winter.The results showed that auditory brainstem response(ABR)thresholds were significantly lower in spring than in winter at a frequency range of 0.5-0.9 kHz.The hearing-sensitivity bandwidth was wider,and the ABR latency was significantly shorter in spring than in winter.No significant differences were found in estradiol,testosterone,and dihydrotestosterone levels in T.scripta elegans between spring and winter.This study is the first to reveal the seasonal variation of peripheral hearing sensitivity in turtles,a special animal group with limited hearing range and less vocalization.Temperature variations may be used to explain these seasonal effects,but further research is required to confirm our findings.展开更多
文摘Multiplicative noise removal problems have attracted much attention in recent years.Unlike additive noise,multiplicative noise destroys almost all information of the original image,especially for texture images.Motivated by the TV-Stokes model,we propose a new two-step variational model to denoise the texture images corrupted by multiplicative noise with a good geometry explanation in this paper.In the first step,we convert the multiplicative denoising problem into an additive one by the logarithm transform and propagate the isophote directions in the tangential field smoothing.Once the isophote directions are constructed,an image is restored to fit the constructed directions in the second step.The existence and uniqueness of the solution to the variational problems are proved.In these two steps,we use the gradient descent method and construct finite difference schemes to solve the problems.Especially,the augmented Lagrangian method and the fast Fourier transform are adopted to accelerate the calculation.Experimental results show that the proposed model can remove the multiplicative noise efficiently and protect the texture well.
基金funding from several sources,including the Chongqing Scientific Research Institution Performance Incentive Project(grant number cstc2022jxjl80007)the Earmarked Fund for China Agriculture Research System(grant number CARS-42-51)+5 种基金the Chongqing Scientific Research Institution Performance Incentive Project(grant number 22527 J)the Key R&D Project in Agriculture and Animal Husbandry of Rongchang(grant number No.22534C-22)Natural Science Foundation of Chongqing Project,grant number CSTB2022NSCQ-MSX0434Natural Science Foundation of Sichuan Project,grant number 2022NSFSC0605Natural Science Foundation of Sichuan Project,grant number 2021YFS0379the Chongqing Technology Innovation and Application Development Project(grant number No.cstc2021ycjh-bgzxm0248)。
文摘Background Domestic goose breeds are descended from either the Swan goose(Anser cygnoides)or the Greylag goose(Anser anser),exhibiting variations in body size,reproductive performance,egg production,feather color,and other phenotypic traits.Constructing a pan-genome facilitates a thorough identification of genetic variations,thereby deepening our comprehension of the molecular mechanisms underlying genetic diversity and phenotypic variability.Results To comprehensively facilitate population genomic and pan-genomic analyses in geese,we embarked on the task of 659 geese whole genome resequencing data and compiling a database of 155 RNA-seq samples.By constructing the pan-genome for geese,we generated non-reference contigs totaling 612 Mb,unveiling a collection of 2,813 novel genes and pinpointing 15,567 core genes,1,324 softcore genes,2,734 shell genes,and 878 cloud genes in goose genomes.Furthermore,we detected an 81.97 Mb genomic region showing signs of genome selection,encompassing the TGFBR2 gene correlated with variations in body weight among geese.Genome-wide association studies utilizing single nucleotide polymorphisms(SNPs)and presence-absence variation revealed significant genomic associations with various goose meat quality,reproductive,and body composition traits.For instance,a gene encoding the SVEP1 protein was linked to carcass oblique length,and a distinct gene-CDS haplotype of the SVEP1 gene exhibited an association with carcass oblique length.Notably,the pan-genome analysis revealed enrichment of variable genes in the“hair follicle maturation”Gene Ontology term,potentially linked to the selection of feather-related traits in geese.A gene presence-absence variation analysis suggested a reduced frequency of genes associated with“regulation of heart contraction”in domesticated geese compared to their wild counterparts.Our study provided novel insights into gene expression features and functions by integrating gene expression patterns across multiple organs and tissues in geese and analyzing population variation.Conclusion This accomplishment originates from the discernment of a multitude of selection signals and candidate genes associated with a wide array of traits,thereby markedly enhancing our understanding of the processes underlying domestication and breeding in geese.Moreover,assembling the pan-genome for geese has yielded a comprehensive apprehension of the goose genome,establishing it as an indispensable asset poised to offer innovative viewpoints and make substantial contributions to future geese breeding initiatives.
基金Supported by the National Natural Science Foundation of China(Nos.42176116,41576126,41890851,U21A6001)the Natural Science Foundation of Guangdong Province(No.2017A030306020)+4 种基金the Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302004)the Rising Star Foundation of the South China Sea Institute of Oceanology(No.NHXX2019ST0101)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2018377)the Science and Technology Planning Project of Guangdong Province of China(No.2021B1212050023)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA19060503)。
文摘Variations of picoplankton groups were investigated over a one-month period in Daya Bay and Sanya Bay,in the northern South China Sea.The two coastal regions exhibited different variation patterns in physicochemical parameters.Moreover,the diel variations of picoplankton groups were different between the two bays.The abundance of the picoplankton in Sanya Bay displayed a pronounced diel variation,while it was not significant in Daya Bay.In addition,some similar patterns of picoplankton abundance were discovered.In the two bays,virioplankton exhibited the smallest fluctuation range,whereas picocyanobacteria fluctuated most markedly.The fluctuation range of picoplankton groups was larger in spring tide than in neap tide,especially in Sanya Bay.Random forest model analysis demonstrated that the variation of picoplankton groups was attributed to physical and chemical factors in Sanya Bay and Daya Bay,respectively.Therefore,our findings suggest that virioplankton abundance can persist more stably in response to changing environmental conditions compared to bacterioplankton and picophytoplankton.
基金financed by the Jiangsu Haizhou Bay National Sea Ranching Demonstration Project(No.D-8005-18-0188)the Shanghai Municipal Science and Technology Commission Local Capacity Construction Project(No.21010502200).
文摘Plankton are an important component of marine protected areas(MPAs),and its communities would require much smaller interpatch distances to ensure connection among MPAs.According to the survey from MPAs dominated by artificial reefs and adjacent waters(estuary area(EA),aquaculture area(AA),artificial reef area(ARA),natural area(NA)and comprehensive effect area(CEA))in Haizhou Bay in spring and autumn,we analyzed phyto-zooplankton composition,abundance and biomass,and correlation with hydrologic variables to gain information about the forces that structure the plankton.The results showed that the dominant zooplankton were copepods(spring,98.9%;autumn,94.2%),while the phytoplankton were mainly composed of Bacillariophyta(spring,61.8%;autumn,95.6%).The RDA results showed that temperature,salinity and depth highly associated with the distribution and composition of plankton species among the habitats than other factors in spring;temperature,Chla and DO had the strongest influence in autumn.The zooplankton in the ARA and AA ecosystems basically contained the same species as those in other habitats,and each habitat also exhibited a relatively unique combination of plankton species.The structures of the EA zooplankton in spring and the EA phytoplankton in both seasons were much different than other habitats,which may have been caused by factors such as currents and tides.We concluded that there exists similarity of the plankton community between artificial reef area and adjacent waters,whereas the EAs may be relatively independent systems.Therefore,these interaction between plankton community should be considered when designing MPA networks,and ocean circulations should be considered more than the environmental factors.
基金the Henan Special Funds for Major Science and Technology,China(221100110400)the Henan Scienti?c and Technological Joint Project for Agricultural Improved Varieties,China(2022010503)the National Natural Science Foundation of China(31902038 and 32072564)。
文摘Seed size is an important agronomic trait in melons that directly affects seed germination and subsequent seedling growth.However,the genetic mechanism underlying seed size in melon remains unclear.In the present study,we employed Bulked-Segregant Analysis sequencing(BSA-seq)to identify a candidate region(~1.35 Mb)on chromosome 6 that corresponds to seed size.This interval was confirmed by QTL mapping of three seed size-related traits from an F2 population across three environments.This mapping region represented nine QTLs that shared an overlapping region on chromosome 6,collectively referred to as qSS6.1.New InDel markers were developed in the qSS6.1 region,narrowing it down to a 68.35 kb interval that contains eight annotated genes.Sequence variation analysis of the eight genes identified a SNP with a C to T transition mutation in the promoter region of MELO3C014002,a leucine-rich repeat receptor-like kinase(LRR-RLK)gene.This mutation affected the promoter activity of the MELO3C014002 gene and was successfully used to differentiate the large-seeded accessions(C-allele)from the small-seeded accessions(T-allele).qRT-PCR revealed differential expression of MELO3C014002 between the two parental lines.Its predicted protein has typical LRR-RLK family domains,and phylogenetic analyses reveled its similarity with the homologs in several plant species.Altogether,these findings suggest MELO3C014002 as the most likely candidate gene involved in melon seed size regulation.Our results will be helpful for better understanding the genetic mechanism regulating seed size in melons and for genetically improving this important trait through molecular breeding pathways.
基金supported by Liangzi Lake reservesupported by the International Partnership Program of Chinese Academy of Sciences [Grant number, 152342KYSB20200021]+1 种基金the National Key R and D Program of China [Grant numbers, 2020YFD0900305, 2018YFD0900801]National Natural Science Foundation of China [Grant numbers, 32001107, 32201285, 32101254]
文摘Macrophyte habitats exhibit remarkable heterogeneity,encompassing the spatial variation of abiotic and biotic components such as changes in water conditions and weather as well as anthropogenic stressors.Environmental factors are thought to be important drivers shaping the genetic and epigenetic variation of aquatic plants.However,the links among genetic diversity,epigenetic variation,and environmental variables remain largely unclear,especially for clonal aquatic plants.Here,we performed population genetic and epigenetic analyses in conjunction with habitat discrimination to elucidate the environmental factors driving intraspecies genetic and epigenetic variation in hornwort(Ceratophyllum demersum)in a subtropical lake.Environmental factors were highly correlated with the genetic and epigenetic variation of C.demersum,with temperature being a key driver of the genetic variation.Lower temperature was detected to be correlated with greater genetic and epigenetic variation.Genetic and epigenetic variation were positively driven by water temperature,but were negatively affected by ambient air temperature.These findings indicate that the genetic and epigenetic variation of this clonal aquatic herb is not related to the geographic feature but is instead driven by environmental conditions,and demonstrate the effects of temperature on local genetic and epigenetic variation in aquatic systems.
基金funded by a key project of the National Natural Science Foundation of China called“Research on the Energy Process of Rapid Change of Arctic”(Grant Nos.41941012 and 41976022)the National Natural Science Foundation of China(Grant Nos.42276239 and 42106221)+1 种基金the Natural Science Foundation of Shandong Province(Grant No.ZR2022MD076)Ph.D Foundation“Variation of Arctic Sea Ice Age and Its Relationship with Atmospheric Circulation Field”(Grant No.PY112101).
文摘Besides the rapid retreating trend of Arctic sea-ice extent(SIE),this study found the most outstanding low-frequency variation of SIE to be a 4-6-year periodic variation.Using a clustering analysis algorithm,the SIE in most ice-covered regions was clustered into two special regions:Region-1 around the Barents Sea and Region-2 around the Canadian Basin,which were located on either side of the Arctic Transpolar Drift.Clear 4-6-year periodic variation in these two regions was identified using a novel method called“running linear fitting algorithm”.The rate of temporal variation of the Arctic SIE was related to three driving factors:the regional air temperature,the sea-ice areal flux across the Arctic Transpolar Drift,and the divergence of sea-ice drift.The 4-6-year periodic variation was found to have always been present since 1979,but the SIE responded to different factors under heavy and light ice conditions divided by the year 2005.The joint contribution of the three factors to SIE variation exceeded 83%and 59%in the two regions,respectively,remarkably reflecting their dynamic mechanism.It is proven that the process of El Niño-Southern Oscillation(ENSO)is closely associated with the three factors,being the fundamental source of the 4-6-year periodic variations of Arctic SIE.
基金supported by the University of Buenos Aires(UBACyT,20020090200117)CONICET(PIP112-200901-00011)grants to GJF.
文摘Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population dynamics.Despite numerous studies on this subject in north-temperate environments,there is a lack of equivalent studies at similar latitudes in the south.Here,we used a 14-year dataset of capture,banding,and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens(Troglodytes aedon bonariae).We evaluated temporal variation in sur-vival and the effect of environmental(climatic)and demographic variables(adult abundance,total number of fledglings produced during each breeding season)on survival estimators.We found that the probability of adult survival decreased as the abundance of breeding adults increased.This density-dependent effect could be related to the resident lifestyle of southern House Wrens,which could determine an intense competition for territories and resources that ultimately would affect their survival.
基金supported by the National Natural Science Foundation of China (Grant No. 42192564)Guangdong Major Project of Basic and Applied Basic Research (Grant No. 2020B0301030004)the Ministry of Science and Technology of the People's Republic of China (Grant No.2020YFA0608802)。
文摘El Ni?o–Southern Oscillation(ENSO) exhibits a distinctive phase-locking characteristic, first expressed during its onset in boreal spring, developing during summer and autumn, reaching its peak towards winter, and decaying over the next spring. Several studies have demonstrated that this feature arises as a result of seasonal variation in the growth rate of ENSO as expressed by the sea surface temperature(SST). The bias towards simulating the phase locking of ENSO by many state-of-the-art climate models is also attributed to the unrealistic depiction of the growth rate. In this study, the seasonal variation of SST growth rate in the Ni?o-3.4 region(5°S–5°N, 120°–170°W) is estimated in detail based on the mixed layer heat budget equation and recharge oscillator model during 1981–2020. It is suggested that the consideration of a variable mixed layer depth is essential to its diagnostic process. The estimated growth rate has a remarkable seasonal cycle with minimum rates occurring in spring and maximum rates evident in autumn. More specifically, the growth rate derived from the meridional advection(surface heat flux) is positive(negative) throughout the year. Vertical diffusion generally makes a negative contribution to the evolution of growth rate and the magnitude of vertical entrainment represents the smallest contributor. Analysis indicates that the zonal advective feedback is regulated by the meridional immigration of the intertropical convergence zone, which approaches its southernmost extent in February and progresses to its northernmost location in September, and dominates the seasonal variation of the SST growth rate.
基金funding support from the National Natural Science Foundation of China(Grant Nos.42077262 and 42077261).
文摘A complete road-soft ground model is established in this paper to study the dynamic responses caused by vehicle loads and/or daily temperature variation.A dynamic thermo-elastic model is applied to capturing the behavior of the rigid pavement,the base course,and the subgrade,while the soft ground is characterized using a dynamic thermo-poroelastic model.Solutions to the road-soft ground system are derived in the Laplace-Hankel transform domain.The time domain solutions are obtained using an integration approach.The temperature,thermal stress,pore water pressure,and displacement responses caused by the vehicle load and the daily temperature variation are presented.Results show that obvious temperature change mainly exists within 0.3 m of the road when subjected to the daily temperature variation,whereas the stress responses can still be found in deeper places because of the thermal swelling/shrinkage deformation within the upper road structures.Moreover,it is important to consider the coupling effects of the vehicle load and the daily temperature variation when calculating the dynamic responses inside the road-soft ground system.
基金supported by the Hainan Province Science and Technology Special Fund,China(ZDYF2023XDNY086)the Project of Sanya Yazhou Bay Science and Technology City,China(SCKJ-JYRC-2022-87)+2 种基金the Natural Science Foundation of Guangdong Province,China(2023A1515012052 and 2023A1515012092)the Guangzhou Science and Technology Plan Project,China(2023A04J1452 and 2023A04J0749)the Double First-class Discipline Promotion Project,China(2021B10564001).
文摘Seed vigor is a crucial trait for the direct seeding of rice.Here we examined the genetic regulation of seed vigor traits in rice,including germination index(GI)and germination potential(GP),using a genome-wide association study approach.One major quantitative trait locus,qGI6/qGP6,was identified simultaneously for both GI and GP.The candidate gene encoding the cytochrome c oxidase subunit 5B(OsCOX5B)was validated for qGI6/qGP6.The disruption of OsCOX5B caused the vigor traits to be significantly lower in Oscox5b mutants than in the japonica Nipponbare wild type(WT).Gene co-expression analysis revealed that OsCOX5B influences seed vigor mainly by modulating the tricarboxylic acid cycle process.The glucose levels were significantly higher while the pyruvic acid and adenosine triphosphate levels were significantly lower in Oscox5b mutants than in WT during seed germination.The elite haplotype of OsCOX5B facilitates seed vigor by increasing its expression during seed germination.Thus,we propose that OsCOX5B is a potential target for the breeding of rice varieties with enhanced seed vigor for direct seeding.
基金The National Key R&D Program of China under contract No.2022YFC2807604the Basic Scientific Fund for National Public Research Institutes of China under contract Nos 2022S02,2022Q03 and 2018S02+3 种基金the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2018SDKJ0105-3the National Natural Science Foundation of China under contract Nos 41876030,41976021,41876231,4190060432 and 41706220the program Impact and Response of Antarctic Seas to Climate Change under contract No.IRASCC 01-01-01Athe Taishan Scholars Project Fund under contract No.ts20190963。
文摘Mesoscale eddies are a prominent oceanic phenomenon that plays an important role in oceanic mass transport and energy conversion.Characterizing by rotational speed,the eddy intensity is one of the most fundamental properties of an eddy.However,the seasonal spatiotemporal variation in eddy intensity has not been examined from a global ocean perspective.In this study,we unveil the seasonal spatiotemporal characteristics of eddy intensity in the global ocean by using the latest satellite-altimetry-derived eddy trajectory data set.The results suggest that the eddy intensity has a distinct seasonal variation,reaching a peak in spring while attaining a minimum in autumn in the Northern Hemisphere and the opposite in the Southern Hemisphere.The seasonal variation of eddy intensity is more intense in the tropical-subtropical transition zones within latitudinal bands between 15°and 30°in the western Pacific Ocean,the northwestern Atlantic Ocean,and the eastern Indian Ocean because baroclinic instability in these areas changes sharply.Further analysis found that the seasonal variation of baroclinic instability precedes the eddy intensity by a phase of 2–3 months due to the initial perturbations needing time to grow into mesoscale eddies.
基金supported by grants from the National Key Research and Development Program of China(2023YFF1000404,2022YFF10001501)the National Natural Science Foundation of China(32171971)。
文摘As an essential crop that provides vegetable oil and protein,soybean(Glycine max(L.)Merr.)is widely planted all over the world.However,the scarcity of water resources worldwide has seriously impacted on the quality and yield of soybean.To address this,exploring excellent genes for improving drought resistance in soybean is crucial.In this study,we identified natural variations of GmFNSII-2(flavone synthase II)significantly affect the drought resistance of soybeans.Through sequence analysis of GmFNSII-2 in 632 cultivated and 44 wild soybeans nine haplotypes were identified.The full-length allele GmFNSII-2^(C),but not the truncated allele GmFNSII-2^(A) possessing a nonsense nucleotide variation,increased enzyme activity.Further research found that GmDREB3,known to increase soybean drought resistance,bound to the promoter region of GmFNSII-2^(C).GmDREB3 positively regulated the expression of GmFNSII-2^(C),increased flavone synthase abundance and improved the drought resistance.Furthermore,a singlebase mutation in the GmFNSII-2^(C) promoter generated an additional drought response element(CCCCT),which had stronger interaction strength with GmDREB3 and increased its transcriptional activity under drought conditions.The frequency of drought-resistant soybean varieties with Hap 1(Pro:GmFNSII-2^(C))has increased,suggesting that this haplotype may be selected during soybean breeding.In summary,GmFNSII-2^(C) could be used for molecular breeding of drought-tolerant soybean.
基金supported by the National Natural Science Foundation of China(NSFC,31970564,32000397,32171982)the Fundamental Research Funds for the Central Universities(2662023PY004)。
文摘"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.
基金supported in part by the Open Fund of State Key Laboratory of Integrated Chips and Systems,Fudan Universityin part by the National Science Foundation of China under Grant No.62304133 and No.62350610271.
文摘Reducing the process variation is a significant concern for resistive random access memory(RRAM).Due to its ultrahigh integration density,RRAM arrays are prone to lithographic variation during the lithography process,introducing electrical variation among different RRAM devices.In this work,an optical physical verification methodology for the RRAM array is developed,and the effects of different layout parameters on important electrical characteristics are systematically investigated.The results indicate that the RRAM devices can be categorized into three clusters according to their locations and lithography environments.The read resistance is more sensitive to the locations in the array(~30%)than SET/RESET voltage(<10%).The increase in the RRAM device length and the application of the optical proximity correction technique can help to reduce the variation to less than 10%,whereas it reduces RRAM read resistance by 4×,resulting in a higher power and area consumption.As such,we provide design guidelines to minimize the electrical variation of RRAM arrays due to the lithography process.
基金supported by the Natural Science Foundation of Hunan Province(2023JJ40078)the Scientific Research Project of Hunan Provincial Education Department(No.22C0573)+2 种基金the National Natural Science Foundation of China(51478477,51878668)Guizhou Provincial Department of Transportation Foundation(2017-122058)Foundation of Guizhou Provincial Science and Technology Department([2018]2815).
文摘Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass.The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method.The numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in advance.The results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.
基金Supported by the Hunan Provincial Science Fund for Distinguished Young Scholars(No.2023JJ10053)the National Natural Science Foundation of China(No.42276205)。
文摘The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the dynamic parameters of the ISWs in the northern South China Sea(SCS)were studied based on the reanalysis of long-term temperature and salinity datasets.The results for spectrum analysis show that there are definite geographical differences for the periodic variation of the parameters:in shallow water,all parameters vary with a wave period of one year,while in deep water wave components of the parameters at other frequencies exist.Using wavelet analysis,the wavelet power spectral densities in deep water exhibited an inter-annual variation pattern.For example,the wave component of the dispersion coefficient with a wave period of about half a year reached its power peak once every two years.Based on previous work,this inter-annual variation pattern was deduced to be caused by dynamic processes.In further work on the regulatory mechanisms,empirical orthogonal function(EOF)decomposition was performed.It was found that the modes of the dispersion coefficient have different geographical distributions,explaining the reason why the wave components in different frequencies appeared in different locations.The numerical simulation results confirm that the variations in the parameters of the ISWs derived from the eKdV equation could affect the waveforms significantly because of changes in the polarity of the ISWs.Therefore,the periodic variations of the dynamic parameters are related to the geographical location because of dynamic processes operating.
基金funded by the West Light Foundation of The Chinese Academy of Sciencesnational youth talent support programYunnan youth talents plan(YNWR-QNBJ-2018-183 to Y.N.)。
文摘Flower constancy describes the phenomenon that pollinators tend to successively visit flowers of a single species during foraging,reducing reproductive interference in natural communities.The extent of flower constancy is largely determined by the floral traits of co-flowering species.Both higher inter-specific and lower intraspecific differences of floral traits should contribute to a higher level of flower constancy.However,previous studies mainly focused on interspecific difference,and the intraspecific variation(consistency)of floral traits received much less attention.We hypothesise that selection may favour lower intraspecific floral trait variation in communities composed of multiple co-flowering congeners.We investigated the floral colour variation of three focal Pedicularis species that share pollinators in 19communities composed of either single or multiple Pedicularis species.Colour was quantified using image-based colour analysis as perceived by pollinators.We found that most of the intrapopulation floral colour variation was below the colour discrimination threshold of bumblebees,implying strongly constrained by the visual selection by pollinators.Contrary to the hypothesis,there is no significant difference in intraspecific floral colour variation between different community contexts.It may be due to the relatively large interspecific floral colour differences of most co-flowering species.The influence of community context on intraspecific variation may be reflected in floral traits other than colours.
基金The Chinese Academy of Sciences(CAS)Key Deployment Project of Centre for Ocean Mega-Research of Science under contract No.COMS2020Q07the Open Fund Project of Key Laboratory of Marine Environmental Information Technology,Ministry of Natural Resourcesthe National Natural Science Foundation of China under contract No.41901133.
文摘Arctic sea ice is broadly regarded as an indicator and amplifier of global climate change.The rapid changes in Arctic sea ice have been widely concerned.However,the spatiotemporal changes in the horizontal and vertical dimensions of Arctic sea ice and its asymmetry during the melt and freeze seasons are rarely quantified simultaneously based on multiple sources of the same long time series.In this study,the spatiotemporal variation and freeze-thaw asymmetry of Arctic sea ice were investigated from both the horizontal and vertical dimensions during 1979–2020 based on remote sensing and assimilation data.The results indicated that Arctic sea ice was declining at a remarkably high rate of–5.4×10^(4) km^(2)/a in sea ice area(SIA)and–2.2 cm/a in sea ice thickness(SIT)during 1979 to 2020,and the reduction of SIA and SIT was the largest in summer and the smallest in winter.Spatially,compared with other sub-regions,SIA showed a sharper declining trend in the Barents Sea,Kara Sea,and East Siberian Sea,while SIT presented a larger downward trend in the northern Canadian Archipelago,northern Greenland,and the East Siberian Sea.Regarding to the seasonal trend of sea ice on sub-region scale,the reduction rate of SIA exhibited an apparent spatial heterogeneity among seasons,especially in summer and winter,i.e.,the sub-regions linked to the open ocean exhibited a higher decline rate in winter;however,the other sub-regions blocked by the coastlines presented a greater decline rate in summer.For SIT,the sub-regions such as the Beaufort Sea,East Siberian Sea,Chukchi Sea,Central Arctic,and Canadian Archipelago always showed a higher downward rate in all seasons.Furthermore,a striking freeze-thaw asymmetry of Arctic sea ice was also detected.Comparing sea ice changes in different dimensions,sea ice over most regions in the Arctic showed an early retreat and rapid advance in the horizontal dimension but late melting and gradual freezing in the vertical dimension.The amount of sea ice melting and freezing was disequilibrium in the Arctic during the considered period,and the rate of sea ice melting was 0.3×10^(4) km^(2)/a and 0.01 cm/a higher than that of freezing in the horizontal and vertical dimensions,respectively.Moreover,there were notable shifts in the melting and freezing of Arctic sea ice in 1997/2003 and 2000/2004,respectively,in the horizontal/vertical dimension.
基金funded by the Natural Science Foundation of Hainan Province(320QN256 to TW)the High-level Talent Project of the Hainan Natural Science Foundation(322RC661 to TW)+1 种基金the National Natural Science Foundation of China(31860608 to JW)the Specific Research Fund of the Innovation Platform for Academicians of Hainan Province.
文摘Seasonal variation of hearing sensitivity has been observed in many vertebrate groups with obvious vocal behaviors.Circulating hormones,conspecific calling signals,and temperature are potential factors that drive these plasticity patterns.Turtles have a hearing range that appears to be limited to under 1.5 kHz and are often thought to be non-vocal;thus,they are commonly neglected in vocal communication research.In this study,we aimed to determine whether the auditory phenotype exhibits seasonal variation in sensitivity and to analyze the potential factors driving such variation patterns in turtles.We measured hearing sensitivity and sex hormone levels in female(estradiol)and male(testosterone and dihydrotestosterone)Red-eared sliders(Trachemys scripta elegans)during spring and winter.The results showed that auditory brainstem response(ABR)thresholds were significantly lower in spring than in winter at a frequency range of 0.5-0.9 kHz.The hearing-sensitivity bandwidth was wider,and the ABR latency was significantly shorter in spring than in winter.No significant differences were found in estradiol,testosterone,and dihydrotestosterone levels in T.scripta elegans between spring and winter.This study is the first to reveal the seasonal variation of peripheral hearing sensitivity in turtles,a special animal group with limited hearing range and less vocalization.Temperature variations may be used to explain these seasonal effects,but further research is required to confirm our findings.
