Rural settlement is the basic spatial unit for compact communities in rural area. Scientific exploration of spatial-temporal differentiation and its influencing factors is the premise of spatial layout rationalization...Rural settlement is the basic spatial unit for compact communities in rural area. Scientific exploration of spatial-temporal differentiation and its influencing factors is the premise of spatial layout rationalization. Based on land use data of Liangshan Yi Autonomous Prefecture(hereinafter referred to as Liangshan Prefecture) in Sichuan Province, China from 1980 to 2020, compactness index, fractal dimension, imbalance index, location entropy and the optimal parameters-based geographical detector(OPGD) model are used to analyze the spatial-temporal evolution of the morphological characteristics of rural settlements, and to explore the influence of natural geographical factors, socioeconomic factors, and policy factors on the spatial differentiation of rural settlements. The results show that:(1) From 1980 to 2020, the rural settlements area in Liangshan Prefecture increased by 15.96 km^(2). In space, the rural settlements are generally distributed in a local aggregation, dense in the middle and sparse around the periphery. In 2015, the spatial density and expansion index of rural settlements reached the peak.(2) From 1980 to 2020, the compactness index decreased from 0.7636 to 0.7496, the fractal dimension increased from 1.0283 to 1.0314, and the fragmentation index decreased from 0.1183 to 0.1047. The spatial morphological structure of rural settlements tended to be loose, the shape contour tended to be complex, the degree of fragmentation decreased, and the spatial distribution was significantly imbalanced.(3) The results of OPGD detection in 2015 show that the influence of each factor is slope(0.2371) > traffic accessibility(0.2098) > population(0.1403) > regional GDP(0.1325) > elevation(0.0987) > poverty alleviation(0). The results of OPGD detection in 2020 show that the influence of each factor is slope(0.2339) > traffic accessibility(0.2198) > population(0.1432) > regional GDP(0.1219) > poverty alleviation(0.0992) > elevation(0.093). Natural geographical factors(slope and elevation) are the basic factors affecting the spatial distribution of rural settlements, and rural settlements are widely distributed in the river valley plain and the second half mountain area. Socioeconomic factors(traffic accessibility, population, and regional GDP) have a greater impact on the spatial distribution of rural settlements, which is an important factor affecting the spatial distribution of rural settlements. Policy factors such as poverty alleviation relocation have an indispensable impact on the spatial distribution of rural settlements. The research results can provide decisionmaking basis for the spatial arrangement of rural settlements in Liangshan Prefecture, and optimize the implementation of rural revitalization policies.展开更多
The genus Scincella Mittleman,1950 of the family Scincidae currently includes 38 species."To date,however,taxonomic assessment remains challenging.Here,phylogenetic analyses based on DNA sequences of four mitocho...The genus Scincella Mittleman,1950 of the family Scincidae currently includes 38 species."To date,however,taxonomic assessment remains challenging.Here,phylogenetic analyses based on DNA sequences of four mitochondrial genes supported a putative new species from Sichuan Province,Southwest China,as an independent lineage.Uncorrected genetic distance of 16S rRNA between the new species and closest congener was 8%,and the population was morphologically distinguishable from all other known congeners.We herein describe the Scincella population as anew species based on both phylogeny and comparative morphology.The new species can be distinguished from its congeners by a combination of the following morphological characters:(1)body slender,mediumsized,snout-vent length 35.0-62.1 mm;(2)infralabials seven,rarely eight;(3)supraciliaries 5-7;(4)tympanum deeply sunk without lobules;(5)midbody scale-row counts 27-30;(6)dorsal scales smooth and enlarged,paravertebral scale-row counts 60-75,ventral scalerow counts 46-59,gulars 25-30;(7)upper edge of lateral longitudinal stripes relatively straight with six rows of dorsal scales in middle;(8)number of enlarged,undivided lamellae beneath fingerⅣ9-11,number of enlarged,undivided lamellae beneath toeⅣ13-16;(9)ventral side of tail densely ornamented with dark brown or black spots;and(10)grayish-brown discontinuous regular dorsal stripes 5-7,distinct black dorsolateral stripes,starting from posterior corner of eye and continuing to lateral side of tail.A diagnostic key to all Scincella members from China is also provided The new species is currently only known from Wenchuan and Lixian counties,Sichuan Province,China,and brings the number of Scincella species in China to 12.This study emphasizes the incompleteness of knowledge on herpetodiversity in China.展开更多
The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally.China is home to the most diverse primate species in the Northern hemisphere,which face severe e...The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally.China is home to the most diverse primate species in the Northern hemisphere,which face severe ecological threats due to the expansion of modern agriculture,extensive exploitation and consumption of natural resources,and excessive land development during its transition from an agricultural to a modern society.In response,China has implemented various ecological conservation measures,including habitat restoration and protection.These efforts have made substantial strides in biodiversity conservation,with certain regions witnessing an increase in primate populations.In the current study,we conducted a systematic review of historical documents and field research data related to Chinese primates,evaluating the endangered status of primate species in China.Despite improvements in the habitats of most primate species and some population growth,many species still face severe threats,including declining and small populations.Species such as the Myanmar snub-nosed monkey(Rhinopithecus strykeri),eastern black crested gibbon(Nomascus nasutus),and Hainan gibbon(N.hainanus)remain particularly vulnerable due to their limited distribution ranges and extremely small populations.Insufficient scientific data,fragmented information,and not enough studies in conservation biology further compound the challenges.Moreover,there is a notable lack of detailed population monitoring data for species such as the Bengal slow loris(Nycticebus bengalensis),pygmy slow loris(N.pygmaeus),Indochinese gray langur(Trachypithecus crepusculus),Shortridge’s langur(T.shortridgei),and capped langur(T.pileatus),which hinders the development of practical and targeted conservation management strategies.Therefore,for national biodiversity conservation,there is an urgent need for specialized primate surveys,enhancing habitat protection and restoration,and increasing focus on cross-border conservation strategies and regional cooperation.There is also a need to establish a comprehensive and systematic research database platform,conduct continuous and in-depth research in primate biology,and actively engage in the scientific assessment of ecotourism.Additionally,strengthening public awareness and education on wildlife conservation remains essential.Such integrated and systematic efforts will provide scientific support for the current and future conservation and management of primate species in China.展开更多
China is undergoing a rapid urbanization process,and urbanization will have a direct impact on regional ecosystems and affect regional ecosystem services.Considering the mountainous counties in Southwestern China as t...China is undergoing a rapid urbanization process,and urbanization will have a direct impact on regional ecosystems and affect regional ecosystem services.Considering the mountainous counties in Southwestern China as the research object,this study reveals the spatial clustering characteristics of four typical ecosystem services(food production,soil conservation,water yield and carbon sequestration)as well as the trade-offs and synergies among ecosystem services in different urbanized areas.At the same time,piecewise linear regression is used to determine the threshold of the influence of urbanization on ecosystem services.The results indicate that:1)There are spatial autocorrelations among the four typical ecosystem services;with strong clustering characteristics,the positive correlation types are"clustered"locally;and with significant spatial heterogeneity,the negative correlation types are scattered and mainly appear in the highly urbanized area.2)There are also remarkable differences in the relationship among various ecosystem services in different urbanized areas,and in particular,there are marked trade-offs between food production and carbon sequestration in the moderately urbanized area and the highly urbanized area.However,there are synergies between them in the lowly urbanized area.3)With an increase in the compounded night light index(CNLI),water yield,carbon sequestration,food production and overall ecosystem services values present an increasing-decreasing trend,the soil conservation function value shows a decreasing-increasing trend.The response of water yield,carbon sequestration,food production,and overall ecosystem services to the compounded night light index(CNLI)has a threshold of 1.2642,1.4833,1.3388,1.5146 and 1.2237,respectively.Based on the detected relationships between urbanization and ecosystem services,this study provides a theoretical reference for the selection of urbanization development models in key ecological functional areas.展开更多
Metallic ore mining causes heavy metal pollution worldwide.However,the fate of heavy metals in agrosystems with long-term contamination has been poorly studied.Dongchuan District(Yunnan,southwest China),located at the...Metallic ore mining causes heavy metal pollution worldwide.However,the fate of heavy metals in agrosystems with long-term contamination has been poorly studied.Dongchuan District(Yunnan,southwest China),located at the middle reaches of the Xiaojiang River,is a well-known 2000-year-old copper mining site.In this work,a survey on soil heavy metal contents was conducted using a handheld X-ray fluorescence instrument to understand the general contamination of heavy metals in the Xiaojiang River Basin.Furthermore,river water,soil,and rice samples at six sites along the fluvial/alluvial fans of the river were collected and analyzed to implement an environmental assessment and an evaluation of irrigated agrosystem.V,Zn,and Cu soil levels(1724,1047,and 696mg·kg-1,respectively)far exceeded background levels.The geo-accumulation indexes(Igeo)showed that cultivated soils near the mining sites were polluted by Cd and Cu,followed by Zn,V,Pb,Cr,Ni,and U.The pollution index(Pi)indicated that rice in the area was heavily polluted with Pb,Cr,Cd,Ni,Zn,and Cu.The difference in orders of metal concentrations between the soil and rice heavy metal contamination was related to the proportion of bioavailable heavy metals in the soil.The crop consumption risk assessment showed that the hazard quotient exceeded the safe threshold,indicating a potential carcinogenic risk to consumers.The Nemerow integrated pollution index and health index indicated that the middle of the river(near the mining area)was the heaviest polluted site.展开更多
To realize the sustainable development of the economy of West China is not merely a great economic problem, butalso a great national problem and political issue. The economic activity is a practical activity for the e...To realize the sustainable development of the economy of West China is not merely a great economic problem, butalso a great national problem and political issue. The economic activity is a practical activity for the economic subject. Theeconomic development view, values, and the natural view of the economic subject determine the choice of the behavior of themain body in the economic activity. Only the behavior of the economic subject according with its demands could make theeconomy of west China have a sustainable development. Therefore, establishing the development view, the values and naturalview of the economic subject for sustainable development becomes a realistic problem that is worth of thinking.展开更多
Wine culture is considered as an indispensible part of the culture in different countries. Distinctive differences exist between Chinese wine culture and the wine culture in western countries due to their historical b...Wine culture is considered as an indispensible part of the culture in different countries. Distinctive differences exist between Chinese wine culture and the wine culture in western countries due to their historical backgrounds, different values, cultures and customs, etc. A general study of the comparison between Chinese wine culture and western wine culture is given in this paper in order to help us have a better understanding of the wine culture and make us be aware of showing mutual respect for each other.展开更多
A Ni–P alloy gradient coating consisting of multiple electroless Ni–P layers with various phosphorus contents was prepared on the aviation aluminum alloy. Several characterization and electrochemical techniques were...A Ni–P alloy gradient coating consisting of multiple electroless Ni–P layers with various phosphorus contents was prepared on the aviation aluminum alloy. Several characterization and electrochemical techniques were used to characterize the different Ni–P coatings’ morphologies, phase structures, elemental compositions, and corrosion protection. The gradient coating showed good adhesion and high corrosion and wear resistance, enabling the application of aluminum alloy in harsh environments. The results showed that the double zinc immersion was vital in obtaining excellent adhesion (81.2 N). The optimal coating was not peeled and shredded even after bending tests with angles higher than 90°and was not corroded visually after 500 h of neutral salt spray test at 35℃. The high corrosion resistance was attributed to the misaligning of these micro defects in the three different nickel alloy layers and the amorphous structure of the high P content in the outer layer. These findings guide the exploration of functional gradient coatings that meet the high application requirement of aluminum alloy parts in complicated and harsh aviation environments.展开更多
The regeneration of Tetracentron sinense Oliv.is poor in the understory and in open areas due to the charac-teristics of natural regeneration of the species on forest edges and in gaps.It is unclear whether different ...The regeneration of Tetracentron sinense Oliv.is poor in the understory and in open areas due to the charac-teristics of natural regeneration of the species on forest edges and in gaps.It is unclear whether different light intensities in various habitats affect eco-physiological characteristics of saplings and their natural regeneration.In this study,the light intensity in T.sinense habitats was simulated by artificial shading(L1:100%NS(natural sunlight)in the open;L2:50%NS in a forest gap or edge;L3:10%NS in understory)to investigate differences in morphology,leaf structure,physiology,and photosynthesis of 2-year-old sap-lings,and to analyze the mechanism of light intensity on sapling establishment.Significant differences were observed in morphology(including leaf area,and specific leaf area)under different light intensities.Compared to L1 and L3,chloroplast structure in L2 was intact.With increasing time,superoxide dismutase(SOD)and catalase(CAT)activities in L2 became gradually higher than under the other light intensities,while malondialdehyde(MDA)content was opposite.Shading decreased osmoregulation substance contents of leaves but increased chlorophyll.The results suggest that light intensities significantly affect the eco-physiological characteristics of T.sinense saplings and they would respond most favorably at intermediate levels of light by optimizing eco-physiological characteristics.Therefore,50%natural sunlight should be created to promote saplings establishment and population recovery of T.sinense during in situ conservation,including sowing mature seeds in forest edges or gaps and providing appropriate shade protection for seedlings and saplings in the open.展开更多
We employ an efficient method for identifying γ-ray sources across the entire sky,leveraging advanced algorithms from Fermipy,and cleverly utilizing the Galactic diffuse background emission model to partition the ent...We employ an efficient method for identifying γ-ray sources across the entire sky,leveraging advanced algorithms from Fermipy,and cleverly utilizing the Galactic diffuse background emission model to partition the entire sky into72 regions,thereby greatly enhancing the efficiency of discovering new sources throughout the sky through multithreaded parallel computing.After confirming the reliability of the new method,we applied it for the first time to analyze data from the Fermi Large Area Telescope(Fermi-LAT)encompassing approximately 15.41 yr of all-sky surveys.Through this analysis,we successfully identified 1379 new sources with significance levels exceeding 4σ,of which 497 sources exhibited higher significance levels exceeding 5σ.Subsequently,we performed a systematic analysis of the spatial extension,spectra,and light variation characteristics of these newly identified sources.We identified 21 extended sources and 23 sources exhibiting spectral curvature above 10 GeV.Additionally,we identified 44 variable sources above 1 GeV.展开更多
By considering the negative cosmological constant Λ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the D-dimensional dyonic Ad S black holes(BHs) with quasitopological electromagnet...By considering the negative cosmological constant Λ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the D-dimensional dyonic Ad S black holes(BHs) with quasitopological electromagnetism in Einstein–Gauss–Bonnet(EGB) gravity. The results indicate that the small/large BH phase transition that is similar to the van der Waals(vdW) liquid/gas phase transition always exists for any spacetime dimensions. Interestingly, we then find that this BH system exhibits a more complex phase structure in 6-dimensional case that is missed in other dimensions.Specifically, it shows for D = 6 that we observed the small/intermediate/large BH phase transitions in a specific parameter region with the triple point naturally appeared. Moreover, when the magnetic charge turned off, we still observed the small/intermediate/large BH phase transitions and triple point only in 6-dimensional spacetime, which is consistent with the previous results. However, for the dyonic Ad S BHs with quasitopological electromagnetism in Einstein–Born–Infeld(EBI) gravity, the novel phase structure composed of two separate coexistence curves observed by Li et al. [Phys. Rev. D105 104048(2022)] disappeared in EGB gravity. This implies that this novel phase structure is closely related to gravity theories, and seems to have nothing to do with the effect of quasitopological electromagnetism. In addition, it is also true that the critical exponents calculated near the critical points possess identical values as mean field theory. Finally, we conclude that these findings shall provide some deep insights into the intriguing thermodynamic properties of the dyonic Ad S BHs with quasitopological electromagnetism in EGB gravity.展开更多
Mediated by pollenflow,natural hybridization is deemed a crucial factor that propels speciation infloral plants.Despite the fact that the diversity of Epimedium species is concentrated mainly in Southwestern China,the p...Mediated by pollenflow,natural hybridization is deemed a crucial factor that propels speciation infloral plants.Despite the fact that the diversity of Epimedium species is concentrated mainly in Southwestern China,the poten-tial impact of interspecific pollination on natural hybridization has yet to be empirically scrutinized.To explore this,we studied theflowering period and the visitors offlowers in three frequently overlapping Epimedium species at Jinchengshan National Forest Park,located in Nanchong,Sichuan Province.Additionally,we performed a ser-ies of pollination experiments to examine breeding systems and hybrid compatibility.Morphologically,Epime-dium pubescens and Epimedium wushanense are clearly distinct and easily recognizable byflower morphology,while the putative hybrid is morphologically intermediate between them.Our observation revealed that E.pub-escens and E.wushanense had 15 days of overlapping anthesis.Both species are self-incompatible and require pol-linator services for successful reproduction.Although their pollinators differ in quantity and species,Lasioglossum sp.(Hymenoptera:Halictidae)visited all three species.Artificial pollination revealed no breeding barriers among the three species,and the resulting hybrid seeds exhibited fertility.The overlapping time offlowering,commonfloral visitors,and compatibility of hybrids may be important factors contributing to successful interspecific pol-lination and speciation for natural hybrid species of E.pubescens and E.wushanense.Consequently,the role of potential interspecific pollination is crucial for hybrid speciation and the evolutionary dynamics of Epimedium species.展开更多
Organic-inorganic MoO_(3)/PI(MoPI)composites were prepared using a simple one-pot thermal copolymerization method.The resulting composites exhibited enhanced photocatalytic activity for the selective oxidation of benz...Organic-inorganic MoO_(3)/PI(MoPI)composites were prepared using a simple one-pot thermal copolymerization method.The resulting composites exhibited enhanced photocatalytic activity for the selective oxidation of benzylamine to N-benzylidene benzylamine(N-BDBA)in ambient air under simulated solar light irradiation compared to pristine MoO_(3) or polyimide(PI).In particular,the MoPI composite with a 0.3:1 molar ratio of Mo to melamine,referred to as MoPI-0.3,demonstrated the best performance in the photo-oxidation of benzylamine,achieving a benzylamine conversion of 95%with a N-BDBA selectivity exceeding 99%after 3 h irradiation.The enhanced photocatalytic activity of the MoPI-0.3 catalyst was attributed to the formation of a direct Z-scheme heterojunction between MoO_(3) and PI,facilitating more efficient separation of the photoinduced electrons and holes.Additionally,the MoPI-0.3 composite maintained considerably high activity over four consecutive cycles,highlighting its good stability and recyclability.Furthermore,the MoPI-0.3 composite could photo-oxidize benzylamine derivatives and heterocyclic amines to their corresponding imines,demonstrating the universal applicability of this composite catalyst.展开更多
We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),a...We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),and ensure thatαis positive to avoid any singularity problems.The equation derived for the shadow radius indicates that it increases as the event horizon radius increases,making it an independent variable for determining BH temperature.By investigating the PT curve in relation to shadows,we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH PT.Furthermore,the results indicate that an increase in the parameterαcorresponds to a decrease in the temperature of the BH.By utilizing the relationship between the temperature and the shadow radius,it is possible to obtain the thermal profile of the Gauss-Bonnet AdS BH.It is evident that there is an N-type variation in temperature for pressures P<P_(c).Additionally,as the parameterαincreases,the region covered by shadow expands while the temperature decreases.The utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior.展开更多
The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)mission is designed to monitor the Gamma-Ray Bursts(GRBs)associated with gravitational waves and other high-energy transient sources...The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)mission is designed to monitor the Gamma-Ray Bursts(GRBs)associated with gravitational waves and other high-energy transient sources.The mission consists of two microsatellites which are planned to operate at the opposite sides of the Earth.Each GECAM satellite could detect and localize GRBs in about 8 keV-5 MeV with its 25 Gamma-Ray Detectors(GRDs).In this work,we report the in-flight energy calibration of GRDs using the characteristic gamma-ray lines in the background spectra,and show their performance evolution during the commissioning phase.Besides,a preliminary cross-calibration of energy response with Fermi GBM data is also presented,validating the energy response of GRDs.展开更多
Alzheimer’s disease(AD)is a complex,progressive neurodegenerative disorder.The subtle and insidious onset of its pathogenesis makes early detection of a formidable challenge in both contemporary neuroscience and clin...Alzheimer’s disease(AD)is a complex,progressive neurodegenerative disorder.The subtle and insidious onset of its pathogenesis makes early detection of a formidable challenge in both contemporary neuroscience and clinical practice.In this study,we introduce an advanced diagnostic methodology rooted in theMed-3D transfermodel and enhanced with an attention mechanism.We aim to improve the precision of AD diagnosis and facilitate its early identification.Initially,we employ a spatial normalization technique to address challenges like clarity degradation and unsaturation,which are commonly observed in imaging datasets.Subsequently,an attention mechanism is incorporated to selectively focus on the salient features within the imaging data.Building upon this foundation,we present the novelMed-3D transfermodel,designed to further elucidate and amplify the intricate features associated withADpathogenesis.Our proposedmodel has demonstrated promising results,achieving a classification accuracy of 92%.To emphasize the robustness and practicality of our approach,we introduce an adaptive‘hot-updating’auxiliary diagnostic system.This system not only enables continuous model training and optimization but also provides a dynamic platform to meet the real-time diagnostic and therapeutic demands of AD.展开更多
Adaptive optics systems are the most powerful tools to counteract the image blurring caused by atmospheric turbulence,allowing ground-based telescopes to capture high-resolution images.A critical parameter influencing...Adaptive optics systems are the most powerful tools to counteract the image blurring caused by atmospheric turbulence,allowing ground-based telescopes to capture high-resolution images.A critical parameter influencing adaptive optics system performance is the atmospheric refractive index structure constant,C_(n)^(2),which characterizes the intensity of atmospheric optical turbulence as a function of altitude.Given its simplicity,the lunar scintillometer is the preferred method for detecting atmospheric turbulence in challenging environments like Dome A in Antarctica,where sites are still in the developmental stages and local environmental conditions are extremely harsh.However,optimizing the performance of such instruments requires carefully determining the baseline configuration of photon sensors according to each site's specific optical turbulence profile characteristics.This study uses a Monte Carlo method to identify the optimal configuration for the KunLun Turbulence Profiler(KLTP),an instrument comparable to the lunar scintillometer,developed for use at Dome A.Simulations conducted using the obtained optimal baseline configuration recovered three different model optical turbulence profiles,demonstrating the effectiveness of our method in obtaining an optimal baseline configuration.Our approach can be easily applied to baseline design for similar turbulence profilers at other sites.展开更多
Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal ...Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal structure,temporal and dynamical evolutionary stages of individual stars and the host cluster.The most powerful tool for such studies is time-domain photometric observations.This paper follows the route of our previous work,concentrating on a photometric search for variable stars in NGC 884.The target cluster is the companion of NGC869,forming the well-known double cluster system that is gravitationally bound.From the observation run in 2016 November,a total of 9247 B-band CCD images and 8218Ⅴ-band CCD images were obtained.We detected a total of 15 stars with variability in visual brightness,including five Be stars,three eclipsing binaries,and seven of unknown types.Two new variable stars were discovered in this work.We also compared the variable star content of NGC 884 with its companion NGC 869.展开更多
Long period variable(LPV)stars are very promising distance indicators in the infrared bands.We selected asymptotic giant branch(AGB)stars in the Large and Small Magellanic Cloud(LMC and SMC)from the Gaia Data Release ...Long period variable(LPV)stars are very promising distance indicators in the infrared bands.We selected asymptotic giant branch(AGB)stars in the Large and Small Magellanic Cloud(LMC and SMC)from the Gaia Data Release 3 LPV catalog,and classified them into oxygen-rich(O-rich)and carbon-rich(C-rich)AGB stars.Using the Wide-field Infrared Survey Explorer database,we determined the W1-and W2-band period-luminosity relations(PLRs)for each pulsation-mode sequence of AGB stars.The dispersion of the PLRs of O-rich AGB stars in sequences C'and C is relatively small,around 0.14 mag.The PLRs of LMC and SMC are consistent in each sequence.In the W2 band,the PLR of large-amplitude C-rich AGB stars is steeper than that of small-amplitude C-rich AGB stars,due to their more circumstellar dust.By two methods,we find that some PLR sequences of O-rich AGB stars in the LMC are dependent on metallicity.The coefficients of the metallicity effect areβ=-0.533±0.213 mag dex~1andβ=-0.767±0.158 mag dex~1for sequence C in W1 and W2 bands,respectively.The significance of the metallicity effect in W1 band for the four sequences is 2.2-3.5σ.Both of these imply that distance measurements using O-rich Mira may need to take the metallicity effect into account.展开更多
Realtime trigger and localization of bursts are the key functions of GECAM,an all-sky gamma-ray monitor launched on 2020 December 10.We developed a multifunctional trigger and localization software operating in the CP...Realtime trigger and localization of bursts are the key functions of GECAM,an all-sky gamma-ray monitor launched on 2020 December 10.We developed a multifunctional trigger and localization software operating in the CPU of the GECAM Electronic Box.This onboard software has the following features:high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation,dedicated localization algorithm optimized for both short and long bursts,and low time latency of the trigger information which is downlinked through the Global Short Message Communication service of the global BeiDou navigation system.This paper provides a detailed description of the design and development of the trigger and localization software system for GECAM.It covers the general design,workflow,the main functions,and the algorithms used in the system.The paper also includes on-ground trigger tests using simulated gamma-ray bursts generated by a dedicated X-ray tube,as well as an overview of the performance for real celestial bursts during its in-orbit operation.展开更多
基金funded by the National Natural Science Foundation of China (Grant Nos. 41971015)Doctoral research program of China West Normal University (Grant Nos.19E067)。
文摘Rural settlement is the basic spatial unit for compact communities in rural area. Scientific exploration of spatial-temporal differentiation and its influencing factors is the premise of spatial layout rationalization. Based on land use data of Liangshan Yi Autonomous Prefecture(hereinafter referred to as Liangshan Prefecture) in Sichuan Province, China from 1980 to 2020, compactness index, fractal dimension, imbalance index, location entropy and the optimal parameters-based geographical detector(OPGD) model are used to analyze the spatial-temporal evolution of the morphological characteristics of rural settlements, and to explore the influence of natural geographical factors, socioeconomic factors, and policy factors on the spatial differentiation of rural settlements. The results show that:(1) From 1980 to 2020, the rural settlements area in Liangshan Prefecture increased by 15.96 km^(2). In space, the rural settlements are generally distributed in a local aggregation, dense in the middle and sparse around the periphery. In 2015, the spatial density and expansion index of rural settlements reached the peak.(2) From 1980 to 2020, the compactness index decreased from 0.7636 to 0.7496, the fractal dimension increased from 1.0283 to 1.0314, and the fragmentation index decreased from 0.1183 to 0.1047. The spatial morphological structure of rural settlements tended to be loose, the shape contour tended to be complex, the degree of fragmentation decreased, and the spatial distribution was significantly imbalanced.(3) The results of OPGD detection in 2015 show that the influence of each factor is slope(0.2371) > traffic accessibility(0.2098) > population(0.1403) > regional GDP(0.1325) > elevation(0.0987) > poverty alleviation(0). The results of OPGD detection in 2020 show that the influence of each factor is slope(0.2339) > traffic accessibility(0.2198) > population(0.1432) > regional GDP(0.1219) > poverty alleviation(0.0992) > elevation(0.093). Natural geographical factors(slope and elevation) are the basic factors affecting the spatial distribution of rural settlements, and rural settlements are widely distributed in the river valley plain and the second half mountain area. Socioeconomic factors(traffic accessibility, population, and regional GDP) have a greater impact on the spatial distribution of rural settlements, which is an important factor affecting the spatial distribution of rural settlements. Policy factors such as poverty alleviation relocation have an indispensable impact on the spatial distribution of rural settlements. The research results can provide decisionmaking basis for the spatial arrangement of rural settlements in Liangshan Prefecture, and optimize the implementation of rural revitalization policies.
基金funded by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0501)the Sichuan Science and Technology Program(2021JDJQ0002)Biological Resources Programme,Chinese Academy of Sciences(KFJ-BRP-017-65)。
文摘The genus Scincella Mittleman,1950 of the family Scincidae currently includes 38 species."To date,however,taxonomic assessment remains challenging.Here,phylogenetic analyses based on DNA sequences of four mitochondrial genes supported a putative new species from Sichuan Province,Southwest China,as an independent lineage.Uncorrected genetic distance of 16S rRNA between the new species and closest congener was 8%,and the population was morphologically distinguishable from all other known congeners.We herein describe the Scincella population as anew species based on both phylogeny and comparative morphology.The new species can be distinguished from its congeners by a combination of the following morphological characters:(1)body slender,mediumsized,snout-vent length 35.0-62.1 mm;(2)infralabials seven,rarely eight;(3)supraciliaries 5-7;(4)tympanum deeply sunk without lobules;(5)midbody scale-row counts 27-30;(6)dorsal scales smooth and enlarged,paravertebral scale-row counts 60-75,ventral scalerow counts 46-59,gulars 25-30;(7)upper edge of lateral longitudinal stripes relatively straight with six rows of dorsal scales in middle;(8)number of enlarged,undivided lamellae beneath fingerⅣ9-11,number of enlarged,undivided lamellae beneath toeⅣ13-16;(9)ventral side of tail densely ornamented with dark brown or black spots;and(10)grayish-brown discontinuous regular dorsal stripes 5-7,distinct black dorsolateral stripes,starting from posterior corner of eye and continuing to lateral side of tail.A diagnostic key to all Scincella members from China is also provided The new species is currently only known from Wenchuan and Lixian counties,Sichuan Province,China,and brings the number of Scincella species in China to 12.This study emphasizes the incompleteness of knowledge on herpetodiversity in China.
基金supported by the National Natural Science Foundation of China(32371563)and Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31020302)。
文摘The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally.China is home to the most diverse primate species in the Northern hemisphere,which face severe ecological threats due to the expansion of modern agriculture,extensive exploitation and consumption of natural resources,and excessive land development during its transition from an agricultural to a modern society.In response,China has implemented various ecological conservation measures,including habitat restoration and protection.These efforts have made substantial strides in biodiversity conservation,with certain regions witnessing an increase in primate populations.In the current study,we conducted a systematic review of historical documents and field research data related to Chinese primates,evaluating the endangered status of primate species in China.Despite improvements in the habitats of most primate species and some population growth,many species still face severe threats,including declining and small populations.Species such as the Myanmar snub-nosed monkey(Rhinopithecus strykeri),eastern black crested gibbon(Nomascus nasutus),and Hainan gibbon(N.hainanus)remain particularly vulnerable due to their limited distribution ranges and extremely small populations.Insufficient scientific data,fragmented information,and not enough studies in conservation biology further compound the challenges.Moreover,there is a notable lack of detailed population monitoring data for species such as the Bengal slow loris(Nycticebus bengalensis),pygmy slow loris(N.pygmaeus),Indochinese gray langur(Trachypithecus crepusculus),Shortridge’s langur(T.shortridgei),and capped langur(T.pileatus),which hinders the development of practical and targeted conservation management strategies.Therefore,for national biodiversity conservation,there is an urgent need for specialized primate surveys,enhancing habitat protection and restoration,and increasing focus on cross-border conservation strategies and regional cooperation.There is also a need to establish a comprehensive and systematic research database platform,conduct continuous and in-depth research in primate biology,and actively engage in the scientific assessment of ecotourism.Additionally,strengthening public awareness and education on wildlife conservation remains essential.Such integrated and systematic efforts will provide scientific support for the current and future conservation and management of primate species in China.
基金supported by the 135 Strategic Program of the Institute of Mountain Hazards and Environment, CAS (NO.SDS-135-1703)the Science and Technology Service Network Initiative (No. KFJ-STS-QYZD-060)+2 种基金Doctor Startup Foundation of China West Normal University (N0. 412650)the Sichuan Center for Rural Development Research Project (No. CR1811)Scientific Research Innovation Team Projects of China West Normal University (N0. CXTD2018-10)
文摘China is undergoing a rapid urbanization process,and urbanization will have a direct impact on regional ecosystems and affect regional ecosystem services.Considering the mountainous counties in Southwestern China as the research object,this study reveals the spatial clustering characteristics of four typical ecosystem services(food production,soil conservation,water yield and carbon sequestration)as well as the trade-offs and synergies among ecosystem services in different urbanized areas.At the same time,piecewise linear regression is used to determine the threshold of the influence of urbanization on ecosystem services.The results indicate that:1)There are spatial autocorrelations among the four typical ecosystem services;with strong clustering characteristics,the positive correlation types are"clustered"locally;and with significant spatial heterogeneity,the negative correlation types are scattered and mainly appear in the highly urbanized area.2)There are also remarkable differences in the relationship among various ecosystem services in different urbanized areas,and in particular,there are marked trade-offs between food production and carbon sequestration in the moderately urbanized area and the highly urbanized area.However,there are synergies between them in the lowly urbanized area.3)With an increase in the compounded night light index(CNLI),water yield,carbon sequestration,food production and overall ecosystem services values present an increasing-decreasing trend,the soil conservation function value shows a decreasing-increasing trend.The response of water yield,carbon sequestration,food production,and overall ecosystem services to the compounded night light index(CNLI)has a threshold of 1.2642,1.4833,1.3388,1.5146 and 1.2237,respectively.Based on the detected relationships between urbanization and ecosystem services,this study provides a theoretical reference for the selection of urbanization development models in key ecological functional areas.
基金funded by National Key Research and Development Program of China (Grant No. 2017YFC0504902)National Key Technology R&D Program of China (Grant No. 2012BAC06B02)
文摘Metallic ore mining causes heavy metal pollution worldwide.However,the fate of heavy metals in agrosystems with long-term contamination has been poorly studied.Dongchuan District(Yunnan,southwest China),located at the middle reaches of the Xiaojiang River,is a well-known 2000-year-old copper mining site.In this work,a survey on soil heavy metal contents was conducted using a handheld X-ray fluorescence instrument to understand the general contamination of heavy metals in the Xiaojiang River Basin.Furthermore,river water,soil,and rice samples at six sites along the fluvial/alluvial fans of the river were collected and analyzed to implement an environmental assessment and an evaluation of irrigated agrosystem.V,Zn,and Cu soil levels(1724,1047,and 696mg·kg-1,respectively)far exceeded background levels.The geo-accumulation indexes(Igeo)showed that cultivated soils near the mining sites were polluted by Cd and Cu,followed by Zn,V,Pb,Cr,Ni,and U.The pollution index(Pi)indicated that rice in the area was heavily polluted with Pb,Cr,Cd,Ni,Zn,and Cu.The difference in orders of metal concentrations between the soil and rice heavy metal contamination was related to the proportion of bioavailable heavy metals in the soil.The crop consumption risk assessment showed that the hazard quotient exceeded the safe threshold,indicating a potential carcinogenic risk to consumers.The Nemerow integrated pollution index and health index indicated that the middle of the river(near the mining area)was the heaviest polluted site.
文摘To realize the sustainable development of the economy of West China is not merely a great economic problem, butalso a great national problem and political issue. The economic activity is a practical activity for the economic subject. Theeconomic development view, values, and the natural view of the economic subject determine the choice of the behavior of themain body in the economic activity. Only the behavior of the economic subject according with its demands could make theeconomy of west China have a sustainable development. Therefore, establishing the development view, the values and naturalview of the economic subject for sustainable development becomes a realistic problem that is worth of thinking.
文摘Wine culture is considered as an indispensible part of the culture in different countries. Distinctive differences exist between Chinese wine culture and the wine culture in western countries due to their historical backgrounds, different values, cultures and customs, etc. A general study of the comparison between Chinese wine culture and western wine culture is given in this paper in order to help us have a better understanding of the wine culture and make us be aware of showing mutual respect for each other.
基金financially supported by the National Natural Science Foundation of China (No.52271073)。
文摘A Ni–P alloy gradient coating consisting of multiple electroless Ni–P layers with various phosphorus contents was prepared on the aviation aluminum alloy. Several characterization and electrochemical techniques were used to characterize the different Ni–P coatings’ morphologies, phase structures, elemental compositions, and corrosion protection. The gradient coating showed good adhesion and high corrosion and wear resistance, enabling the application of aluminum alloy in harsh environments. The results showed that the double zinc immersion was vital in obtaining excellent adhesion (81.2 N). The optimal coating was not peeled and shredded even after bending tests with angles higher than 90°and was not corroded visually after 500 h of neutral salt spray test at 35℃. The high corrosion resistance was attributed to the misaligning of these micro defects in the three different nickel alloy layers and the amorphous structure of the high P content in the outer layer. These findings guide the exploration of functional gradient coatings that meet the high application requirement of aluminum alloy parts in complicated and harsh aviation environments.
基金funded by the National Natural Science Foundation of China (No.32070371)the Innovation Team Funds of China West Normal University (No.KCXTD2022-4)+1 种基金the fund of Sichuan Meigu Dafegnding National Nature Reserve (No.mgdfd2022-13)Sichuan Micang Mountain National Nature Reserve (No.N5108212022000043)。
文摘The regeneration of Tetracentron sinense Oliv.is poor in the understory and in open areas due to the charac-teristics of natural regeneration of the species on forest edges and in gaps.It is unclear whether different light intensities in various habitats affect eco-physiological characteristics of saplings and their natural regeneration.In this study,the light intensity in T.sinense habitats was simulated by artificial shading(L1:100%NS(natural sunlight)in the open;L2:50%NS in a forest gap or edge;L3:10%NS in understory)to investigate differences in morphology,leaf structure,physiology,and photosynthesis of 2-year-old sap-lings,and to analyze the mechanism of light intensity on sapling establishment.Significant differences were observed in morphology(including leaf area,and specific leaf area)under different light intensities.Compared to L1 and L3,chloroplast structure in L2 was intact.With increasing time,superoxide dismutase(SOD)and catalase(CAT)activities in L2 became gradually higher than under the other light intensities,while malondialdehyde(MDA)content was opposite.Shading decreased osmoregulation substance contents of leaves but increased chlorophyll.The results suggest that light intensities significantly affect the eco-physiological characteristics of T.sinense saplings and they would respond most favorably at intermediate levels of light by optimizing eco-physiological characteristics.Therefore,50%natural sunlight should be created to promote saplings establishment and population recovery of T.sinense during in situ conservation,including sowing mature seeds in forest edges or gaps and providing appropriate shade protection for seedlings and saplings in the open.
基金the Natural Science Foundation Youth Program of Sichuan Province(2023NSFSC1350)the Doctoral Initiation Fund of West China Normal University(22kE040)+2 种基金the Open Fund of Key Laboratory of Astroparticle Physics of Yunnan Province(2022Zibian3)the Sichuan Youth Science and Technology Innovation Research Team(21CXTD0038)the National Natural Science Foundation of China(NSFC,Grant No.12303048)。
文摘We employ an efficient method for identifying γ-ray sources across the entire sky,leveraging advanced algorithms from Fermipy,and cleverly utilizing the Galactic diffuse background emission model to partition the entire sky into72 regions,thereby greatly enhancing the efficiency of discovering new sources throughout the sky through multithreaded parallel computing.After confirming the reliability of the new method,we applied it for the first time to analyze data from the Fermi Large Area Telescope(Fermi-LAT)encompassing approximately 15.41 yr of all-sky surveys.Through this analysis,we successfully identified 1379 new sources with significance levels exceeding 4σ,of which 497 sources exhibited higher significance levels exceeding 5σ.Subsequently,we performed a systematic analysis of the spatial extension,spectra,and light variation characteristics of these newly identified sources.We identified 21 extended sources and 23 sources exhibiting spectral curvature above 10 GeV.Additionally,we identified 44 variable sources above 1 GeV.
基金supported by the National Natural Science Foundation of China (Grant No. 11903025)the Starting Fund of China West Normal University (Grant No. 18Q062)+2 种基金the Sichuan Science and Technology Program (Grant No. 2023ZYD0023)the Sichuan Youth Science and Technology Innovation Research Team (Grant No. 21CXTD0038)the Natural Science Foundation of Sichuan Province (Grant No. 2022NSFSC1833)。
文摘By considering the negative cosmological constant Λ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the D-dimensional dyonic Ad S black holes(BHs) with quasitopological electromagnetism in Einstein–Gauss–Bonnet(EGB) gravity. The results indicate that the small/large BH phase transition that is similar to the van der Waals(vdW) liquid/gas phase transition always exists for any spacetime dimensions. Interestingly, we then find that this BH system exhibits a more complex phase structure in 6-dimensional case that is missed in other dimensions.Specifically, it shows for D = 6 that we observed the small/intermediate/large BH phase transitions in a specific parameter region with the triple point naturally appeared. Moreover, when the magnetic charge turned off, we still observed the small/intermediate/large BH phase transitions and triple point only in 6-dimensional spacetime, which is consistent with the previous results. However, for the dyonic Ad S BHs with quasitopological electromagnetism in Einstein–Born–Infeld(EBI) gravity, the novel phase structure composed of two separate coexistence curves observed by Li et al. [Phys. Rev. D105 104048(2022)] disappeared in EGB gravity. This implies that this novel phase structure is closely related to gravity theories, and seems to have nothing to do with the effect of quasitopological electromagnetism. In addition, it is also true that the critical exponents calculated near the critical points possess identical values as mean field theory. Finally, we conclude that these findings shall provide some deep insights into the intriguing thermodynamic properties of the dyonic Ad S BHs with quasitopological electromagnetism in EGB gravity.
基金This research was supported by the Natural Science Foundation of Sichuan Province(No.2023NSFSC1282)the National General Cultivation Project of China West Normal University(No.19B029)Youth Foundation Specialization of West China Normal University(No.22KB004).
文摘Mediated by pollenflow,natural hybridization is deemed a crucial factor that propels speciation infloral plants.Despite the fact that the diversity of Epimedium species is concentrated mainly in Southwestern China,the poten-tial impact of interspecific pollination on natural hybridization has yet to be empirically scrutinized.To explore this,we studied theflowering period and the visitors offlowers in three frequently overlapping Epimedium species at Jinchengshan National Forest Park,located in Nanchong,Sichuan Province.Additionally,we performed a ser-ies of pollination experiments to examine breeding systems and hybrid compatibility.Morphologically,Epime-dium pubescens and Epimedium wushanense are clearly distinct and easily recognizable byflower morphology,while the putative hybrid is morphologically intermediate between them.Our observation revealed that E.pub-escens and E.wushanense had 15 days of overlapping anthesis.Both species are self-incompatible and require pol-linator services for successful reproduction.Although their pollinators differ in quantity and species,Lasioglossum sp.(Hymenoptera:Halictidae)visited all three species.Artificial pollination revealed no breeding barriers among the three species,and the resulting hybrid seeds exhibited fertility.The overlapping time offlowering,commonfloral visitors,and compatibility of hybrids may be important factors contributing to successful interspecific pol-lination and speciation for natural hybrid species of E.pubescens and E.wushanense.Consequently,the role of potential interspecific pollination is crucial for hybrid speciation and the evolutionary dynamics of Epimedium species.
基金supported by the Opening Project of Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan (LZJ2101)the Fundamental Research Funds of China West Normal University (19D038)
文摘Organic-inorganic MoO_(3)/PI(MoPI)composites were prepared using a simple one-pot thermal copolymerization method.The resulting composites exhibited enhanced photocatalytic activity for the selective oxidation of benzylamine to N-benzylidene benzylamine(N-BDBA)in ambient air under simulated solar light irradiation compared to pristine MoO_(3) or polyimide(PI).In particular,the MoPI composite with a 0.3:1 molar ratio of Mo to melamine,referred to as MoPI-0.3,demonstrated the best performance in the photo-oxidation of benzylamine,achieving a benzylamine conversion of 95%with a N-BDBA selectivity exceeding 99%after 3 h irradiation.The enhanced photocatalytic activity of the MoPI-0.3 catalyst was attributed to the formation of a direct Z-scheme heterojunction between MoO_(3) and PI,facilitating more efficient separation of the photoinduced electrons and holes.Additionally,the MoPI-0.3 composite maintained considerably high activity over four consecutive cycles,highlighting its good stability and recyclability.Furthermore,the MoPI-0.3 composite could photo-oxidize benzylamine derivatives and heterocyclic amines to their corresponding imines,demonstrating the universal applicability of this composite catalyst.
基金Project supported by the National Natural Science Foundation of China (Grant No.11903025)the starting fund of China West Normal University (Grant No.18Q062)+2 种基金the Sichuan Youth Science and Technology Innovation Research Team (Grant No.21CXTD0038)the Chongqing Science and Technology Bureau (Grant No.cstc2022ycjh-bgzxm0161)the Natural Science Foundation of Sichuan Province (Grant No.2022NSFSC1833)。
文摘We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),and ensure thatαis positive to avoid any singularity problems.The equation derived for the shadow radius indicates that it increases as the event horizon radius increases,making it an independent variable for determining BH temperature.By investigating the PT curve in relation to shadows,we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH PT.Furthermore,the results indicate that an increase in the parameterαcorresponds to a decrease in the temperature of the BH.By utilizing the relationship between the temperature and the shadow radius,it is possible to obtain the thermal profile of the Gauss-Bonnet AdS BH.It is evident that there is an N-type variation in temperature for pressures P<P_(c).Additionally,as the parameterαincreases,the region covered by shadow expands while the temperature decreases.The utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior.
基金supported by the Strategic Priority Program on Space Science,the Chinese Academy of Sciences,grant Nos.XDA15360102,XDA15360300 and E02212A02Sthe National Natural Science Foundation of China(Project:12061131007)。
文摘The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)mission is designed to monitor the Gamma-Ray Bursts(GRBs)associated with gravitational waves and other high-energy transient sources.The mission consists of two microsatellites which are planned to operate at the opposite sides of the Earth.Each GECAM satellite could detect and localize GRBs in about 8 keV-5 MeV with its 25 Gamma-Ray Detectors(GRDs).In this work,we report the in-flight energy calibration of GRDs using the characteristic gamma-ray lines in the background spectra,and show their performance evolution during the commissioning phase.Besides,a preliminary cross-calibration of energy response with Fermi GBM data is also presented,validating the energy response of GRDs.
基金funded by the National Natural Science Foundation of China(No.62076044)Scientific Research Foundation of Chongqing University of Technology(No.2020ZDZ015).
文摘Alzheimer’s disease(AD)is a complex,progressive neurodegenerative disorder.The subtle and insidious onset of its pathogenesis makes early detection of a formidable challenge in both contemporary neuroscience and clinical practice.In this study,we introduce an advanced diagnostic methodology rooted in theMed-3D transfermodel and enhanced with an attention mechanism.We aim to improve the precision of AD diagnosis and facilitate its early identification.Initially,we employ a spatial normalization technique to address challenges like clarity degradation and unsaturation,which are commonly observed in imaging datasets.Subsequently,an attention mechanism is incorporated to selectively focus on the salient features within the imaging data.Building upon this foundation,we present the novelMed-3D transfermodel,designed to further elucidate and amplify the intricate features associated withADpathogenesis.Our proposedmodel has demonstrated promising results,achieving a classification accuracy of 92%.To emphasize the robustness and practicality of our approach,we introduce an adaptive‘hot-updating’auxiliary diagnostic system.This system not only enables continuous model training and optimization but also provides a dynamic platform to meet the real-time diagnostic and therapeutic demands of AD.
基金financially supported by the National Natural Science Foundation of China (12373092, 12273027, 11733007, 11873010, 12133010)the Nebula Talents Program of the National Astronomical Observatories, CAS+1 种基金the Sichuan Youth Science and Technology Innovation Research Team (21CXTD0038)the Innovation Team F unds of China West Normal University (KCXTD2022-6).
文摘Adaptive optics systems are the most powerful tools to counteract the image blurring caused by atmospheric turbulence,allowing ground-based telescopes to capture high-resolution images.A critical parameter influencing adaptive optics system performance is the atmospheric refractive index structure constant,C_(n)^(2),which characterizes the intensity of atmospheric optical turbulence as a function of altitude.Given its simplicity,the lunar scintillometer is the preferred method for detecting atmospheric turbulence in challenging environments like Dome A in Antarctica,where sites are still in the developmental stages and local environmental conditions are extremely harsh.However,optimizing the performance of such instruments requires carefully determining the baseline configuration of photon sensors according to each site's specific optical turbulence profile characteristics.This study uses a Monte Carlo method to identify the optimal configuration for the KunLun Turbulence Profiler(KLTP),an instrument comparable to the lunar scintillometer,developed for use at Dome A.Simulations conducted using the obtained optimal baseline configuration recovered three different model optical turbulence profiles,demonstrating the effectiveness of our method in obtaining an optimal baseline configuration.Our approach can be easily applied to baseline design for similar turbulence profilers at other sites.
基金the National Natural Science Foundation of China(NSFC)through grants 12003022,12373035,12233009 and 12173047support from the Youth Innovation Promotion Association of the CAS(grant No.2022055)。
文摘Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal structure,temporal and dynamical evolutionary stages of individual stars and the host cluster.The most powerful tool for such studies is time-domain photometric observations.This paper follows the route of our previous work,concentrating on a photometric search for variable stars in NGC 884.The target cluster is the companion of NGC869,forming the well-known double cluster system that is gravitationally bound.From the observation run in 2016 November,a total of 9247 B-band CCD images and 8218Ⅴ-band CCD images were obtained.We detected a total of 15 stars with variability in visual brightness,including five Be stars,three eclipsing binaries,and seven of unknown types.Two new variable stars were discovered in this work.We also compared the variable star content of NGC 884 with its companion NGC 869.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.12173047,12322306,12003046,12233009,and 12133002)support from the Youth Innovation Promotion Association of the Chinese Academy of Sciences(no.2022055 and 2023065)support from the National Key Research and Development Program of China,grants 2022YFF0503404 and 2019YFA0405504。
文摘Long period variable(LPV)stars are very promising distance indicators in the infrared bands.We selected asymptotic giant branch(AGB)stars in the Large and Small Magellanic Cloud(LMC and SMC)from the Gaia Data Release 3 LPV catalog,and classified them into oxygen-rich(O-rich)and carbon-rich(C-rich)AGB stars.Using the Wide-field Infrared Survey Explorer database,we determined the W1-and W2-band period-luminosity relations(PLRs)for each pulsation-mode sequence of AGB stars.The dispersion of the PLRs of O-rich AGB stars in sequences C'and C is relatively small,around 0.14 mag.The PLRs of LMC and SMC are consistent in each sequence.In the W2 band,the PLR of large-amplitude C-rich AGB stars is steeper than that of small-amplitude C-rich AGB stars,due to their more circumstellar dust.By two methods,we find that some PLR sequences of O-rich AGB stars in the LMC are dependent on metallicity.The coefficients of the metallicity effect areβ=-0.533±0.213 mag dex~1andβ=-0.767±0.158 mag dex~1for sequence C in W1 and W2 bands,respectively.The significance of the metallicity effect in W1 band for the four sequences is 2.2-3.5σ.Both of these imply that distance measurements using O-rich Mira may need to take the metallicity effect into account.
基金supported by the Strategic Priority Research Program on Space Science of the Chinese Academy of Sciences,the support from the Strategic Priority Research Program on Space Science(grant Nos.XDA15360300,XDA15360000,XDA15360102,XDA15052700 and E02212A02S)of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(NSFC,Grant No.12173038)and BeiDou navigation system。
文摘Realtime trigger and localization of bursts are the key functions of GECAM,an all-sky gamma-ray monitor launched on 2020 December 10.We developed a multifunctional trigger and localization software operating in the CPU of the GECAM Electronic Box.This onboard software has the following features:high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation,dedicated localization algorithm optimized for both short and long bursts,and low time latency of the trigger information which is downlinked through the Global Short Message Communication service of the global BeiDou navigation system.This paper provides a detailed description of the design and development of the trigger and localization software system for GECAM.It covers the general design,workflow,the main functions,and the algorithms used in the system.The paper also includes on-ground trigger tests using simulated gamma-ray bursts generated by a dedicated X-ray tube,as well as an overview of the performance for real celestial bursts during its in-orbit operation.