6 results on '"Li, Changchun"'
Search Results
2. Mapping Winter Wheat with Optical and SAR Images Based on Google Earth Engine in Henan Province, China.
- Author
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Li, Changchun, Chen, Weinan, Wang, Yilin, Wang, Yu, Ma, Chunyan, Li, Yacong, Li, Jingbo, and Zhai, Weiguang
- Subjects
- *
WINTER wheat , *SYNTHETIC aperture radar , *OPTICAL images , *NORMALIZED difference vegetation index , *RANDOM forest algorithms - Abstract
The timely and accurate acquisition of winter wheat acreage is crucial for food security. This study investigated the feasibility of extracting the spatial distribution map of winter wheat in Henan Province by using synthetic aperture radar (SAR, Sentinel-1A) and optical (Sentinel-2) images. Firstly, the SAR images were aggregated based on the growth period of winter wheat, and the optical images were aggregated based on the moderate resolution imaging spectroradiometer normalized difference vegetation index (MODIS-NDVI) curve. Then, five spectral features, two polarization features, and four texture features were selected as feature variables. Finally, the Google Earth Engine (GEE) cloud platform was employed to extract winter wheat acreage through the random forest (RF) algorithm. The results show that: (1) aggregated images based on the growth period of winter wheat and sensor characteristics can improve the mapping accuracy and efficiency; (2) the extraction accuracy of using only SAR images was improved with the accumulation of growth period. The extraction accuracy of using the SAR images in the full growth period reached 80.1%; and (3) the identification effect of integrated images was relatively good, which makes up for the shortcomings of SAR and optical images and improves the extraction accuracy of winter wheat. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
3. Li Changchun's Speech at the Award Ceremony on the 10th China Journalist's Day.
- Author
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Li Changchun
- Subjects
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SPECIAL days , *JOURNALISTS , *MASS media & politics - Abstract
The article presents the summary of the speech by Li Changchun, member of the Standing Committee of the Political Bureau of the Communist Party of China (CPC) Central Committee, delivered during the awarding ceremony of the 10th China Journalist's Day on November 8, 2009. He spoke about the 60th anniversary of the new China and the role of the news industry. He also pointed out the CPC's good traditions in the media and propaganda work that the news front inherited and advanced.
- Published
- 2010
4. Overridingly increasing vegetation sensitivity to vapor pressure deficit over the recent two decades in China.
- Author
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Liu, Miao, Yang, Guijun, Yuan, Wenping, Li, Zhenhong, Gao, Meiling, Yang, Yun, Long, Huiling, Meng, Yang, Li, Changchun, Hu, Haitang, Li, Heli, and Yuan, Zhanliang
- Subjects
- *
VAPOR pressure , *BROADLEAF forests , *CLIMATE change , *ARID regions , *DECIDUOUS forests , *CLIMATIC zones - Abstract
• The increasing trend of vapor pressure deficit (VPD) change in 1997–2020 is ten times higher than in 1981–1996. • Increasing VPD promoted cropland and grassland growth in Arid, while inhibited the growth of shrubland. • Significant positive or negative difference in the sensitivity to VPD for the same vegetation under different climatic zones. • The vast majority of vegetation showed a significant increase in the inter-annual trend of the sensitivity to VPD. • The relationship of higher sensitivity with lower VPD is not stable under different vegetation and climatic zones. Vapor pressure deficit (VPD) shows significant spatial and temporal variability in the context of global climate change, which is important for studying the implications of climate change on the structure and function of ecosystems to analyze the effects of VPD on vegetation dynamics. Spatial patterns of vegetation sensitivity to VPD have been recently investigated, however, the feedback of different vegetation types to VPD may vary depending on physiological characteristics, it is unclear how different types influence the sensitivity to VPD. In this study, the ERA5-Land reanalysis time-series dataset was used to analyze the spatial and temporal trends of VPD under different vegetation types. It was found that VPD showed an increasing trend in vegetated areas over the past 20 years with large spatial heterogeneity, generally increasing with drying conditions. On this basis, the spatial patterns of vegetation sensitivity to VPD and temporal trends in sensitivity were evaluated over the past 20 years in China using the enhanced vegetation index (EVI) and near-infrared reflectance of vegetation (NIRv) which can describe vegetation dynamics. The results show that the sensitivities under the two indices have high spatial consistency, with northeastern and central China showing positive sensitivities and southern China showing negative sensitivities, respectively. The positive sensitivities are relatively high for Deciduous Broadleaf Forests (DBF), Deciduous Needleleaf Forests (DNF), Grasslands (GL), and Croplands (CL) types, while the negative sensitivities are larger for Shrublands (SL) and Savannas (SA) types. Under different climatic zones, the sensitivity of CL and GL are independent of climatic zones (both showing positive), while the sensitivity of SL is negative in the Humid zone and positive in the Semi-Arid zone. Temporally, the sensitivity showed a slow increasing trend over the last 20 years. In terms of vegetation types, sensitivities of Evergreen Broadleaf Forests (EBF), DBF, GL and CL types showed a significant increasing trend (p < 0.05), except for the SL type, which showed a significant decreasing trend (p < 0.05). The trends of sensitivity are not affected by the differences in vegetation types (all of them show an increasing trend) under arid and semi-arid conditions, while dry sub-humid and humid have a greater impact on sensitivity trends. The finding of an overall increase in sensitivity suggests a mechanism of erratic change in vegetation growth under climate change. Notably, the increased sensitivity of certain vegetation types (especially GL and CL) suggests that these may become progressively vulnerable to increased VPD as global climate change persists, with the risk of moving from facilitation to inhibition of photosynthesis. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. [Retrospective analysis of the on-site treatment of the coronavirus disease 2019 epidemic on the Costa Crociere cruise].
- Author
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Yang W, Li C, Wang F, Dou K, Cheng Y, Ni B, and Hou X
- Subjects
- COVID-19, China epidemiology, Epidemics, Humans, Retrospective Studies, SARS-CoV-2, Betacoronavirus, Coronavirus Infections epidemiology, Pandemics, Pneumonia, Viral epidemiology
- Abstract
Coronavirus disease 2019 (COVID-19) epidemic is the most widespread global pandemic in the past 100 years. Person-to-person transmission of COVID-19 infection leads to the major threat of human safety and health. At 00:00 on January 24th, 2020, Tianjin City launched the first-level response to the COVID-19 epidemic. At 18:00 on the same day, Management Committee of Dongjiang Free Trade Port Zone of Tianjin received areport that there were 15 people who had fever on the Costa Crociere carrying 4 806 people from Japan back to the home port of Tianjin Dongjiang Cruise. At the same time, there are more than 140 Chinese Hubei tourists. Tianjin Municipal Committee and Government, Tianjin Customs, Binhai New Area District Committee Government, Tianjin Health Commission, Tianjin Binhai New Area Health Commission formed an emergency command center immediately to deal with the epidemic comprehensively. At 06:40 on January 25th, 2020, the medical investigation team made up by Tianjin Binhai New Area Health Commission and Tianjin East Administration of Customs boarded the cruise ship. With reference to the customs inspection and quarantine regulations, in accordance with the Diagnosis and treatment of pneumonia caused by novel coronavirus (trial version 3) for mulated by the National Health Commission of the People's Republic of China and the Novel coronavirus infected pneumonia port control and technology plan (first version) formulated by the General Administration of Customs, combined with the actual situation of cruise ships, the medical investigation team developed the inspection standards, including door-to-door inspections, temperature measurement and epidemiological investigations on all persons on board of the cruise ship. A total of 4 806 person-times were investigated in the affected area, including 3 706 tourists and 1 100 crew members. Seventeen people at high risk of COVID-19 were identified, including three Wuhan tourists. The reports of 2019 novel coronavirus (2019-nCoV) nucleic acid detection on throat swab samples for those who were identified as high risk were returned as all negative at 14:54 on the same day. At 19:30, the medical investigation team completed the investigation and evacuated the cruise ship. The temperature measurement, medical observation and resettlement of passenger were handed over to relevant personnel. After 2 weeks, the follow-up result of 2019-nCoV nucleic acid of 17 high risk people were all negative. The overall command and comprehensive coordination of the onshore command center together with the rigid principles and excellent responds ability of the on-site epidemic investigation team ensured the successful completion of the epidemic investigation work, and also provided reference for further improving the management and disposal capacity of public health emergencies at sea.
- Published
- 2020
- Full Text
- View/download PDF
6. Characterization of genetic polymorphism of novel MHC B-LB II alleles in Chinese indigenous chickens.
- Author
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Xu R, Li K, Chen G, Xu H, Qiang B, Li C, and Liu B
- Subjects
- Alleles, Amino Acid Sequence, Animals, Base Sequence, China, DNA Primers, Gene Frequency, Histocompatibility, Molecular Sequence Data, Sequence Alignment, Sequence Analysis, DNA, Chickens genetics, Genes, MHC Class II genetics, Polymorphism, Genetic
- Abstract
Genetic polymorphism of the major histocompatibility complex (MHC) B-LB II gene was studied by amplification of exon 2 using PCR, followed by cloning and DNA sequencing in eight indigenous Chinese chicken populations. To reveal the genetic variation of the B-LB II gene, 37 types of patterns detected by PCR-SSCP were investigated first, which would be used to screen novel B-LB II sequences within the breeds. The types of PCR-SSCP patterns and final sequencing allowed for the identification of 31 novel MHC B-LB II alleles from 30 unrelated individuals of Chinese chickens that were sampled. These are the first designators for the alleles of chicken MHC B-LB II gene based on the rule of assignment for novel mammalian alleles. Sequence alignment of the 31 B-LB II alleles revealed a total of 68 variable sites in the fragment of exon 2, of which 51 parsimony informative and 17 singleton variable sites were observed. Among the polymorphic sites, the nucleotide substitutions in the first and second positions of the codons accounted for 36.76% and 35.29%, respectively. The sequence similarities between the alleles were estimated to be 90.6%-99.5%. The relative frequencies of synonymous and nonsynonymous nucleotide substitutions within the region were 2.92%+/-0.94% and 14.64%+/-2.67%, respectively. These results indicated that the genetic variation within exon 2 appeared to have largely arisen by gene recombination and balancing selection. Alignment of the deduced amino acid sequences of the beta1 domain coded by exon 2 revealed 6 synonymous mutations and 27 nonsynonymous substitutions at the 33 disparate sites. In particular, the nonsynonymous substitutions at the putative peptide-binding sites are considered to be associated with immunological specificity of MHC B-LB II molecule in Chinese native chickens. These results can provide a molecular biological basis for the study of disease resistance in chicken breeding.
- Published
- 2007
- Full Text
- View/download PDF
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