Understanding the relative roles of local environmental effects and spatial effects on phytoplankton community is of essential importance to study the biogeography of them at regional scale. However, the determinants ...Understanding the relative roles of local environmental effects and spatial effects on phytoplankton community is of essential importance to study the biogeography of them at regional scale. However, the determinants that driving the biogeography of phytoplankton communities in the coastal area of northern Zhejiang still remained unclear. We surveyed phytoplankton community compositions in water columns associated with environmental and spatial influences across five subzones that geographically covering this region over four seasons. Diatoms and dinoflagellates were recorded as the main dominant groups and Coscinodiscus oculs-iridis, Coscinodiscus jonesianus, and Skeletonema costatum, were identified as the major abundant species existing in all seasons.Spatially structured environmental conditions, rather than pure spatial or environmental factors, substantially shaped the biogeography of phytoplankton community, with the former mainly comprised of water temperature,dissolved oxygen, phosphate, pH, and salinity, and the latter referring to a non-negligible factor. This study was the first integrated research that combining environmental filtering with spatial factors in structuring phytoplankton communities at a complete tempo-spatial scale. Our results may facilitate to the further study of harmful algal blooms early-warning in this region.展开更多
Types and structure of plant communities in the Yellow River Delta were investigated by using detrended canonical correspon-dence analyses(DCCAs) and a two-way indicator species analysis(TWINSPAN).The distribution pat...Types and structure of plant communities in the Yellow River Delta were investigated by using detrended canonical correspon-dence analyses(DCCAs) and a two-way indicator species analysis(TWINSPAN).The distribution pattern and influential factors of the plant communities were also analyzed by testing elevation, slope, soil characteristics, longitude and latitude of 134 vegetation samples collected by representative plot sampling methods.Results showed that all the 134 vegetation samples could be divided into seven vegetation groups, separately dominated by Robinia pseucdoacacia, Imperata cylindrical, Miscanthus saccharifleus, Suaeda salsa, Aeluropus sinensis, Phragmites australis and Tamarix chinensis.The vegetation distribution pattern was mainly related to elevation, ground water depth and soil characteristics such as salinity and soluble potassium.Among the factors affecting distribution pattern of the plant communities, the species matrix explained by non-spatial environmental variation accounts for 45.2% of total variation.Spatial variation and spatial-structured environmental variation explain 11.8%, and 2.2%, respectively.Remained 40.8% of undetermined variation is attributed to biological and stochastic factors.展开更多
To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communit...To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communities and the environmental properties of the surface waters surrounding the Five Southern Islands of Miaodao Archipelago were investigated, based on seasonal field survey conducted from November 2012 to August 2013. During the survey, a total of 109 phytoplankton species from 3 groups were identified in the southern waters of Miaodao Archipelago, of which 77 were diatoms, 29 were dinoflagellates, and 3 were chrysophytes. Species number was higher in winter(73), moderate in autumn(70), but lower in summer(31) and spring(27). The species richness index in autumn(5.92) and winter(4.28) was higher than that in summer(2.83) and spring(1.41).The Shannon-Wiener diversity index was high in autumn(2.82), followed by winter(1.99) and summer(1.92), and low in spring(0.07). The species evenness index in autumn(0.46) and summer(0.39) was higher than that in winter(0.32) and spring(0.02). On the basis of principal component analysis(PCA) and redundancy analysis(RDA), we found that dissolved inorganic nitrogen(DIN) and chemical oxygen demand(COD) in spring, COD in summer, p H in autumn, and salinity and oil pollutant in winter, respectively, showed the strongest association with the distribution of phytoplankton diversity. The spatial heterogeneity of the southern waters of Miaodao Archipelago was quite obvious, and three zones, i.e., northeastern, southwestern and inter-island water area, were identified by cluster analysis(CA) based on key environmental variables.展开更多
Quantitative distribution of planktonic amphipoda in the East China Sea is analyzed and the relation with environmental factors and mackerel and scad fishing grounds is studied. The result shows that the characteristi...Quantitative distribution of planktonic amphipoda in the East China Sea is analyzed and the relation with environmental factors and mackerel and scad fishing grounds is studied. The result shows that the characteristic of biomass is great seasonal and interannual variety during the passing three decades. The distribution of planktonic amphipoda basically reflects the movement, decay and intensification of the different water systems in the survey area.展开更多
Due to rapid urbanization and industrialization,the gap between urban and rural development has gradually increased.Rural development problems have been a significant topic of discussion,and are related to people’s l...Due to rapid urbanization and industrialization,the gap between urban and rural development has gradually increased.Rural development problems have been a significant topic of discussion,and are related to people’s livelihoods.This article built a point-axis-region location driving system to analyze the spatial location differentiation of characteristic villages and towns(CVTS)using the kernel density model,and explored the mechanism of location driving factors with a geographical detector model.The results show that vegetables and fruits are the main types of products in CVTS.They account for 27.60%and 34.68%of all types of products,and occur mainly in the east and central regions of China.Moreover,all point-axis-region driving factors have a significant influence on grain crops.The mean values of driving forces of vegetables and fruits are larger than other types of CVTS,and their values are 0.12 and 0.11.The average driving forces on all CVTS in the northeast are higher than those in other regions,especially the driving forces of vegetables and medicinal crops(0.24 and 0.18,respectively).Finally,we proposed that the Chinese government should employ engineering technology,invest on road networks,e-commerce and blockchain technology to optimize the point-axis-region location advantages,to promote the sustainable development of CVTS.The detection of driving mechanisms on spatial location differentiation of CVTS has important research value for location theory and rural region systems research.展开更多
BACKGROUND: Calcitonin gene-related peptide (CGRP) and nerve growth actor (NGF) cam improve spatial learning and memory abilities of rats with cerebral ischemia/reperfusion; however, the effect of combination of them ...BACKGROUND: Calcitonin gene-related peptide (CGRP) and nerve growth actor (NGF) cam improve spatial learning and memory abilities of rats with cerebral ischemia/reperfusion; however, the effect of combination of them on relieving learning and memory injury following cerebral ischemia/reperfusion should be further studied. OBJECTIVE: To study the effects of exogenous CGRP and NGF on learning and memory abilities of rats with focal cerebral ischemia/reperfusion. DESIGN: Randomized controlled animal study. SETTING: Department of Neurosurgery, the Second Hospital of Xiamen; Department of Neurosurgery, the Second Affiliated Hospital of China Medical University; Department of Neurobiology, Basic Medical College of China Medical University. MATERIALS: A total of 30 healthy male SD rats, aged 8 weeks, of clean grade, weighing 250-300 g, were provided by Experimental Animal Department of China Medical University. All rats were randomly divided into sham-operation group, ischemia/reperfusion group and treatment group with 10 in each group. The main reagents were detailed as the follows: 100 g/L chloral hydrate, 0.5 mL CGRP (2 mg/L, Sigma Company, USA), and NGF (1× 106 U/L, 0.5 mL, Siweite Company, Dalian). METHODS: The experiment was carried out in the Department of Neurobiology, Basic Medical College of China Medical University from February to July 2005. Rat models of middle cerebral artery occlusion were established by method of occlusion, 2 hours after that rats were anesthetized and the thread was slightly drawn out for 10 mm under direct staring to perform reperfusion. Rats in the ischemia/reperfusion group received intraperitoneal injection of 1 mL saline via the abdomen at two hours later, while rats in the treatment group at 2 hours later received intraperitoneal injection of 2 mg/L CGRP (0.5 mL) and 1×106 U/L NGF (0.5 mL) once a day for 10 successive days. First administration was accomplished within 15 minutes after ischemia/reperfusion. Rats in the sham-operation group were separated of the vessels without occlusion or administration. The neural function was evaluated with Zea Longa 5-grade scale. Animals with the score of one, two and three points received Morris water-maze test to measure searching time on platform (omitting platform-escaping latency). Meanwhile, leaning and memory abilities of animals were reflected through testing times of passing through platform per minute. MAIN OUTCOME MEASURES: Experimental results of omitting platform-escaping latency and spatial probe. RESULTS: Three and two rats in the ischemia/reperfusion group and treatment group respectively were not in accordance with the criteria in the process, and the rest were involved in the final analysis. ① Comparisons of platform-escaping latency during Morris water-maze test in all the three groups: Ten days after modeling, the platform-escaping latency in the ischemia/reperfusion group was obviously longer than that in sham-operation group (P < 0.01), and was significantly shorter than that in the treatment group (P < 0.01). ② Comparisons of times of passing through platform in all the three groups: Times of passing through platform were remarkably less in the ischemia/reperfusion group than those in the sham-operation group [(1.79±0.39), (4.30±0.73) times/minute, P < 0.01], and those were markedly more in the treatment group than the ischemia/reperfusion group [(3.16±1.03), (1.79±0.39) times/minute, P < 0.01]. CONCLUSION: CGRP and NGF are capable of ameliorating the abilities of spatial learning and memory in MCAO rats, which indicates that CGRP and NGF can protect ischemic neurons.展开更多
The Peiligang culture(ca.7000–5000 cal BC)is the earliest Neolithic culture in the middle Yellow River valley and represents the emergence of cereal farming in the region[1].It has long been considered representative...The Peiligang culture(ca.7000–5000 cal BC)is the earliest Neolithic culture in the middle Yellow River valley and represents the emergence of cereal farming in the region[1].It has long been considered representative of millet farming[2],which requires a dry field,a certain amount of rainfall,and minimal crop management,but new records reveal that mixed farming of millet and rice(Oryza sp.)took place during this period[3].Therefore,it is possible展开更多
A three-wave interaction (3WI) code is developed to study the stimulated Raman scattering (SRS) in both absolute and convective regimes. In the simulations, the time and spatial evolutions of a plasma wave are des...A three-wave interaction (3WI) code is developed to study the stimulated Raman scattering (SRS) in both absolute and convective regimes. In the simulations, the time and spatial evolutions of a plasma wave are described by temporal growth rate and spatial factor, respectively. The spatial factors in different phases and different instability regimes are investigated. It is found that the spatial factor is caused by the finite velocity of the pump wave in the first phase and by damping in the last phase. With inclusion of the spatial factor, the temporal growth rate decreases and the threshold for SRS for a finite frequency mismatch increases. Meanwhile, the effects of wave frequency mismatch on the temporal growth rate are also discussed.展开更多
Urban agglomeration plays a vital role in fostering high-quality and sustainable development in China,where urbanization rates signifi-cantly influence both urban and rural environments,generating different economic a...Urban agglomeration plays a vital role in fostering high-quality and sustainable development in China,where urbanization rates signifi-cantly influence both urban and rural environments,generating different economic and socio-spatial impacts that,in turn,influence carbon emissions in cities.To delve into the influencing mechanisms of carbon emissions,this paper examines the spatio-temporal pattern of carbon emissions across 41 cities in the Yangtze River Delta urban agglomeration in China.It utilizes data on economic,social,and spatial factors from 2012 to 2019 and employs a spatial econometric regression model for analysis.The results indicate that carbon emissions of cities in the urban agglomeration exhibited strong spatial correlation from 2012 to 2019,characterized by relatively stable cold and hot spots,along with continuous outward spread of high-value zones.Economic and social factors demonstrate a significant positive spatial correlation with carbon emissions of a city,with weak spatial spillover effects.Spatial factors exhibit correlations with carbon emissions in both the city and neighboring cities,with strong spatial spillover effects.Moreover,the spatial layout and functional division of cities in the urban agglomeration also significantly impact the spatio-temporal pattern of carbon emissions.展开更多
The purpose of this study is to analyze the climatic characteristics and long-term spatial and temporal variations of haze occurrence in China. The impact factors of haze trends are also discussed. Meteorological data...The purpose of this study is to analyze the climatic characteristics and long-term spatial and temporal variations of haze occurrence in China. The impact factors of haze trends are also discussed. Meteorological data from 1961 to 2012 and daily PM10 concentrations from2003 to 2012 were employed in this study. The results indicate that the annual-average hazy days at all stations have been increasing rapidly from 4 days in 1961 to 18 days in 2012. The maximum number of haze days occur in winter(41.1%) while the minimum occur in summer(10.4%). During 1961-2012, the high occurrence areas of haze shifted from central to south and east regions of China. The Beijing-Tianjin-Hebei(Jing-Jin-Ji) region, Shanxi,Shaanxi, and Henan Province are the high occurrence areas for haze, while the Yangtze River Delta(YRD) and the Pearl River Delta(PRD) have become regions with high haze occurrences in the last 25 years. Temperature and pressure are positively correlated with the number of haze days. However, wind, relative humidity, precipitation, and sunshine duration are negatively correlated with the number of haze days. The key meteorological factors affecting the formation and dissipation of haze vary for high and low altitudes, and are closely related to anthropogenic activities. In recent years, anthropogenic activities have played a more important role in haze occurrences compared with meteorological factors.展开更多
Geographical information systems(GIS)are essential tools for mineral prospectivity modeling(MPM).Three-dimensional(3D)MPM is able to learn the association between geological evidence and mineralization in shallow zone...Geographical information systems(GIS)are essential tools for mineral prospectivity modeling(MPM).Three-dimensional(3D)MPM is able to learn the association between geological evidence and mineralization in shallow zones and thereby build a prospectivity model for deep zones,making it a desirable technique to target deep-seated orebodies.However,existing 3D MPM methods directly generalize the model learned in shallow zones to the deep zones without attention to model transferability caused by the different metallogenic mechanisms between the two zones.In this study,we aim to robustly transfer the prospectivity model learned from shallow zones to deep zones.We cast the 3D MPM as a domain adaptation problem,which is an important realm of transfer learning.Because the metallogenic mechanism can be closely associated with spatial locations,we specifically focus on domain adaption concerning the spatial locations that are ignored by conventional domain adaptation methods.To measure the spatial-associated domain discrepancy,we propose a novel spatial-associated maximum mean discrepancy(SAMMD),which compares the joint distributions of features and spatial locations across domains.Based on the SAMMD criterion,a deep neural network,referred to as the spatial-associated domain adaptation network,is devised to learn cross-domain but mineralization-indicative features for building prospectivity model that is transferable to deep zones.A case study of the world-class Sanshandao gold deposit,in eastern China,was carried out to validate the effectiveness of the proposed methods.The results show that compared with other leading MPM methods and other domain adaption variants,the proposed method has superior prediction accuracy and targeting efficiency,demonstrating the effectiveness and robustness of the proposed method in targeting deep-seated orebodies in areas with different metallogenic mechanisms and no labeled data.展开更多
This paper selected Manyuan Village in Oliver Plain(Ganlanba) as a case study to analyze the climate adaptation of traditional villages in Xishuangbanna Dai Autonomous Prefecture with high temperature and high humidit...This paper selected Manyuan Village in Oliver Plain(Ganlanba) as a case study to analyze the climate adaptation of traditional villages in Xishuangbanna Dai Autonomous Prefecture with high temperature and high humidity. Three main thermal environment elements, i.e., temperature, humidity, and wind speed, were collected for comfort evaluation through Kriging analysis and UTCI equivalent temperature calculation. The research concluded the characteristics of the climate adaptation and the spatial factors affecting the comfort degree of traditional Dai villages, including mountain, vegetation, water body, pavilion and corridor, and underlying surface. Finally, the authors also discussed the spatial optimization proposals to improve the comfort degree of traditional Dai villages.展开更多
基金Ecological Restoration Cost Evaluation in Archipelago Ecosystems:A Case Study in Putuo,Zhoushan Archipelago,East China Sea.
文摘Understanding the relative roles of local environmental effects and spatial effects on phytoplankton community is of essential importance to study the biogeography of them at regional scale. However, the determinants that driving the biogeography of phytoplankton communities in the coastal area of northern Zhejiang still remained unclear. We surveyed phytoplankton community compositions in water columns associated with environmental and spatial influences across five subzones that geographically covering this region over four seasons. Diatoms and dinoflagellates were recorded as the main dominant groups and Coscinodiscus oculs-iridis, Coscinodiscus jonesianus, and Skeletonema costatum, were identified as the major abundant species existing in all seasons.Spatially structured environmental conditions, rather than pure spatial or environmental factors, substantially shaped the biogeography of phytoplankton community, with the former mainly comprised of water temperature,dissolved oxygen, phosphate, pH, and salinity, and the latter referring to a non-negligible factor. This study was the first integrated research that combining environmental filtering with spatial factors in structuring phytoplankton communities at a complete tempo-spatial scale. Our results may facilitate to the further study of harmful algal blooms early-warning in this region.
基金supported by the Na-tional Natural Science Foundation of China (No. 40771172)the orientation project of the Chinese Academy of Sciences (No. kzcx2-yw-308)
文摘Types and structure of plant communities in the Yellow River Delta were investigated by using detrended canonical correspon-dence analyses(DCCAs) and a two-way indicator species analysis(TWINSPAN).The distribution pattern and influential factors of the plant communities were also analyzed by testing elevation, slope, soil characteristics, longitude and latitude of 134 vegetation samples collected by representative plot sampling methods.Results showed that all the 134 vegetation samples could be divided into seven vegetation groups, separately dominated by Robinia pseucdoacacia, Imperata cylindrical, Miscanthus saccharifleus, Suaeda salsa, Aeluropus sinensis, Phragmites australis and Tamarix chinensis.The vegetation distribution pattern was mainly related to elevation, ground water depth and soil characteristics such as salinity and soluble potassium.Among the factors affecting distribution pattern of the plant communities, the species matrix explained by non-spatial environmental variation accounts for 45.2% of total variation.Spatial variation and spatial-structured environmental variation explain 11.8%, and 2.2%, respectively.Remained 40.8% of undetermined variation is attributed to biological and stochastic factors.
基金The Special Project of Science and Technology Fundamental Work from the Ministry of Science and Technology of China under contract No.2012FY112500the National Natural Science Foundation of China under contract Nos 41206111 and 41206112
文摘To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communities and the environmental properties of the surface waters surrounding the Five Southern Islands of Miaodao Archipelago were investigated, based on seasonal field survey conducted from November 2012 to August 2013. During the survey, a total of 109 phytoplankton species from 3 groups were identified in the southern waters of Miaodao Archipelago, of which 77 were diatoms, 29 were dinoflagellates, and 3 were chrysophytes. Species number was higher in winter(73), moderate in autumn(70), but lower in summer(31) and spring(27). The species richness index in autumn(5.92) and winter(4.28) was higher than that in summer(2.83) and spring(1.41).The Shannon-Wiener diversity index was high in autumn(2.82), followed by winter(1.99) and summer(1.92), and low in spring(0.07). The species evenness index in autumn(0.46) and summer(0.39) was higher than that in winter(0.32) and spring(0.02). On the basis of principal component analysis(PCA) and redundancy analysis(RDA), we found that dissolved inorganic nitrogen(DIN) and chemical oxygen demand(COD) in spring, COD in summer, p H in autumn, and salinity and oil pollutant in winter, respectively, showed the strongest association with the distribution of phytoplankton diversity. The spatial heterogeneity of the southern waters of Miaodao Archipelago was quite obvious, and three zones, i.e., northeastern, southwestern and inter-island water area, were identified by cluster analysis(CA) based on key environmental variables.
基金This study was supported by the National Essential Foundation Study Progress Plan“973”of China under contract No.G 1999043700.
文摘Quantitative distribution of planktonic amphipoda in the East China Sea is analyzed and the relation with environmental factors and mackerel and scad fishing grounds is studied. The result shows that the characteristic of biomass is great seasonal and interannual variety during the passing three decades. The distribution of planktonic amphipoda basically reflects the movement, decay and intensification of the different water systems in the survey area.
基金funded by National Natural Science Foundation of China(Grant No.42001192)China Postdoctoral Science Foundation(Grant No.2019M662329)+1 种基金MOE Project of Humanities and Social Sciences(Grant No.20YJCZH070)the Youth Team Project of Shandong University(Grant No.IFYT20004).
文摘Due to rapid urbanization and industrialization,the gap between urban and rural development has gradually increased.Rural development problems have been a significant topic of discussion,and are related to people’s livelihoods.This article built a point-axis-region location driving system to analyze the spatial location differentiation of characteristic villages and towns(CVTS)using the kernel density model,and explored the mechanism of location driving factors with a geographical detector model.The results show that vegetables and fruits are the main types of products in CVTS.They account for 27.60%and 34.68%of all types of products,and occur mainly in the east and central regions of China.Moreover,all point-axis-region driving factors have a significant influence on grain crops.The mean values of driving forces of vegetables and fruits are larger than other types of CVTS,and their values are 0.12 and 0.11.The average driving forces on all CVTS in the northeast are higher than those in other regions,especially the driving forces of vegetables and medicinal crops(0.24 and 0.18,respectively).Finally,we proposed that the Chinese government should employ engineering technology,invest on road networks,e-commerce and blockchain technology to optimize the point-axis-region location advantages,to promote the sustainable development of CVTS.The detection of driving mechanisms on spatial location differentiation of CVTS has important research value for location theory and rural region systems research.
文摘BACKGROUND: Calcitonin gene-related peptide (CGRP) and nerve growth actor (NGF) cam improve spatial learning and memory abilities of rats with cerebral ischemia/reperfusion; however, the effect of combination of them on relieving learning and memory injury following cerebral ischemia/reperfusion should be further studied. OBJECTIVE: To study the effects of exogenous CGRP and NGF on learning and memory abilities of rats with focal cerebral ischemia/reperfusion. DESIGN: Randomized controlled animal study. SETTING: Department of Neurosurgery, the Second Hospital of Xiamen; Department of Neurosurgery, the Second Affiliated Hospital of China Medical University; Department of Neurobiology, Basic Medical College of China Medical University. MATERIALS: A total of 30 healthy male SD rats, aged 8 weeks, of clean grade, weighing 250-300 g, were provided by Experimental Animal Department of China Medical University. All rats were randomly divided into sham-operation group, ischemia/reperfusion group and treatment group with 10 in each group. The main reagents were detailed as the follows: 100 g/L chloral hydrate, 0.5 mL CGRP (2 mg/L, Sigma Company, USA), and NGF (1× 106 U/L, 0.5 mL, Siweite Company, Dalian). METHODS: The experiment was carried out in the Department of Neurobiology, Basic Medical College of China Medical University from February to July 2005. Rat models of middle cerebral artery occlusion were established by method of occlusion, 2 hours after that rats were anesthetized and the thread was slightly drawn out for 10 mm under direct staring to perform reperfusion. Rats in the ischemia/reperfusion group received intraperitoneal injection of 1 mL saline via the abdomen at two hours later, while rats in the treatment group at 2 hours later received intraperitoneal injection of 2 mg/L CGRP (0.5 mL) and 1×106 U/L NGF (0.5 mL) once a day for 10 successive days. First administration was accomplished within 15 minutes after ischemia/reperfusion. Rats in the sham-operation group were separated of the vessels without occlusion or administration. The neural function was evaluated with Zea Longa 5-grade scale. Animals with the score of one, two and three points received Morris water-maze test to measure searching time on platform (omitting platform-escaping latency). Meanwhile, leaning and memory abilities of animals were reflected through testing times of passing through platform per minute. MAIN OUTCOME MEASURES: Experimental results of omitting platform-escaping latency and spatial probe. RESULTS: Three and two rats in the ischemia/reperfusion group and treatment group respectively were not in accordance with the criteria in the process, and the rest were involved in the final analysis. ① Comparisons of platform-escaping latency during Morris water-maze test in all the three groups: Ten days after modeling, the platform-escaping latency in the ischemia/reperfusion group was obviously longer than that in sham-operation group (P < 0.01), and was significantly shorter than that in the treatment group (P < 0.01). ② Comparisons of times of passing through platform in all the three groups: Times of passing through platform were remarkably less in the ischemia/reperfusion group than those in the sham-operation group [(1.79±0.39), (4.30±0.73) times/minute, P < 0.01], and those were markedly more in the treatment group than the ischemia/reperfusion group [(3.16±1.03), (1.79±0.39) times/minute, P < 0.01]. CONCLUSION: CGRP and NGF are capable of ameliorating the abilities of spatial learning and memory in MCAO rats, which indicates that CGRP and NGF can protect ischemic neurons.
基金supported by the National Natural Science Foundation of China (41230104 and 41701233)the National Basic Research Program of China (2015CB953803)+1 种基金the China Postdoctoral Science Foundation (2016M601124)the ‘‘Macroevolutionary Processes and Paleoenvironments of Major Historical Biota” of the Chinese Academy of Sciences (XDPB05)
文摘The Peiligang culture(ca.7000–5000 cal BC)is the earliest Neolithic culture in the middle Yellow River valley and represents the emergence of cereal farming in the region[1].It has long been considered representative of millet farming[2],which requires a dry field,a certain amount of rainfall,and minimal crop management,but new records reveal that mixed farming of millet and rice(Oryza sp.)took place during this period[3].Therefore,it is possible
基金supported by Sci. & Tech.Funds of CAEP(Nos.2010A0102004 and 2010B0102018)National Natural Science Foundation of China(Nos.11075025,10975023,10935003,10835003)
文摘A three-wave interaction (3WI) code is developed to study the stimulated Raman scattering (SRS) in both absolute and convective regimes. In the simulations, the time and spatial evolutions of a plasma wave are described by temporal growth rate and spatial factor, respectively. The spatial factors in different phases and different instability regimes are investigated. It is found that the spatial factor is caused by the finite velocity of the pump wave in the first phase and by damping in the last phase. With inclusion of the spatial factor, the temporal growth rate decreases and the threshold for SRS for a finite frequency mismatch increases. Meanwhile, the effects of wave frequency mismatch on the temporal growth rate are also discussed.
文摘Urban agglomeration plays a vital role in fostering high-quality and sustainable development in China,where urbanization rates signifi-cantly influence both urban and rural environments,generating different economic and socio-spatial impacts that,in turn,influence carbon emissions in cities.To delve into the influencing mechanisms of carbon emissions,this paper examines the spatio-temporal pattern of carbon emissions across 41 cities in the Yangtze River Delta urban agglomeration in China.It utilizes data on economic,social,and spatial factors from 2012 to 2019 and employs a spatial econometric regression model for analysis.The results indicate that carbon emissions of cities in the urban agglomeration exhibited strong spatial correlation from 2012 to 2019,characterized by relatively stable cold and hot spots,along with continuous outward spread of high-value zones.Economic and social factors demonstrate a significant positive spatial correlation with carbon emissions of a city,with weak spatial spillover effects.Spatial factors exhibit correlations with carbon emissions in both the city and neighboring cities,with strong spatial spillover effects.Moreover,the spatial layout and functional division of cities in the urban agglomeration also significantly impact the spatio-temporal pattern of carbon emissions.
基金supported by the CMA’s special Funds for climate change(No.CCSF201439)the CMA’s special Funds for key technology(No.CMAGJ2015M79)the MEP’s Special Funds for Research on Public Welfares(No.201409002)
文摘The purpose of this study is to analyze the climatic characteristics and long-term spatial and temporal variations of haze occurrence in China. The impact factors of haze trends are also discussed. Meteorological data from 1961 to 2012 and daily PM10 concentrations from2003 to 2012 were employed in this study. The results indicate that the annual-average hazy days at all stations have been increasing rapidly from 4 days in 1961 to 18 days in 2012. The maximum number of haze days occur in winter(41.1%) while the minimum occur in summer(10.4%). During 1961-2012, the high occurrence areas of haze shifted from central to south and east regions of China. The Beijing-Tianjin-Hebei(Jing-Jin-Ji) region, Shanxi,Shaanxi, and Henan Province are the high occurrence areas for haze, while the Yangtze River Delta(YRD) and the Pearl River Delta(PRD) have become regions with high haze occurrences in the last 25 years. Temperature and pressure are positively correlated with the number of haze days. However, wind, relative humidity, precipitation, and sunshine duration are negatively correlated with the number of haze days. The key meteorological factors affecting the formation and dissipation of haze vary for high and low altitudes, and are closely related to anthropogenic activities. In recent years, anthropogenic activities have played a more important role in haze occurrences compared with meteorological factors.
基金funded by the National Natural Science Foundation of China(Nos.41972309,42272344,42030809,42072325,72088101)National Key R&D Program of China(No.2019YFC1805905).
文摘Geographical information systems(GIS)are essential tools for mineral prospectivity modeling(MPM).Three-dimensional(3D)MPM is able to learn the association between geological evidence and mineralization in shallow zones and thereby build a prospectivity model for deep zones,making it a desirable technique to target deep-seated orebodies.However,existing 3D MPM methods directly generalize the model learned in shallow zones to the deep zones without attention to model transferability caused by the different metallogenic mechanisms between the two zones.In this study,we aim to robustly transfer the prospectivity model learned from shallow zones to deep zones.We cast the 3D MPM as a domain adaptation problem,which is an important realm of transfer learning.Because the metallogenic mechanism can be closely associated with spatial locations,we specifically focus on domain adaption concerning the spatial locations that are ignored by conventional domain adaptation methods.To measure the spatial-associated domain discrepancy,we propose a novel spatial-associated maximum mean discrepancy(SAMMD),which compares the joint distributions of features and spatial locations across domains.Based on the SAMMD criterion,a deep neural network,referred to as the spatial-associated domain adaptation network,is devised to learn cross-domain but mineralization-indicative features for building prospectivity model that is transferable to deep zones.A case study of the world-class Sanshandao gold deposit,in eastern China,was carried out to validate the effectiveness of the proposed methods.The results show that compared with other leading MPM methods and other domain adaption variants,the proposed method has superior prediction accuracy and targeting efficiency,demonstrating the effectiveness and robustness of the proposed method in targeting deep-seated orebodies in areas with different metallogenic mechanisms and no labeled data.
基金funded by the National Key Technologies R&D Program:Comprehensive Demonstration of Disaster Prevention and Mitigation Technology for Ethnic Villages in Southwest China(2020YFD1100705)National Natural Science Foundation of China:Genealogical Study on the Revitalization of Traditional Settlements Along the Tea Horse Road in Yunnan and Tibet in the Perspective of Spatio-Temporal Continuity(51968029)National Natural Science Foundation of China for Youth Science Fund:Methods for Identifying Spatial Planning of Ecological Rehabilitation by Integrating Ecosystem Services and Stakeholders’Well-Being(42101269)。
文摘This paper selected Manyuan Village in Oliver Plain(Ganlanba) as a case study to analyze the climate adaptation of traditional villages in Xishuangbanna Dai Autonomous Prefecture with high temperature and high humidity. Three main thermal environment elements, i.e., temperature, humidity, and wind speed, were collected for comfort evaluation through Kriging analysis and UTCI equivalent temperature calculation. The research concluded the characteristics of the climate adaptation and the spatial factors affecting the comfort degree of traditional Dai villages, including mountain, vegetation, water body, pavilion and corridor, and underlying surface. Finally, the authors also discussed the spatial optimization proposals to improve the comfort degree of traditional Dai villages.