39 results on '"Xia An"'
Search Results
2. An Exploration of China-Africa Cooperation in Higher Education: Opportunities and Challenges in Open Distance Learning
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Zhu, Xia and Chikwa, Gladson
- Abstract
Cognisant of the wide range of cooperation between China and Africa and the existing strong Sino-African relationship, this article explores the international cooperation between Africa and China in the higher education domain, especially in the field of Open Distance Learning (ODL). The study employed data triangulation relying on both secondary and primary sources to address the main research questions. It sheds light on the development of ODL in Chinese Higher Education Institutions (HEIs) with a focus on professional development of university teachers. The article argues that ODL is crucial for emerging economies' sustainable development. Key factors such as political, technological and socio-cultural features play a crucial role in the development and effective implementation of ODL. By exploring the potential opportunities and identifying related challenges, this article contributes to an understanding of how mutually beneficial partnerships between African universities and Chinese HEIs can be developed within the wider framework of Sino-African relationship.
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- 2021
3. Comprehensive analysis of the 'NAC' gene family in 'Elaeis guineensis'
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Xiao, Yong, Fan, Haikuo, Ma, Jianwei, Lei, Xintao, Wang, Yong, Cao, Hongxin, Zhou, Lixia, Zhang, Yong, and Xia, Wei
- Published
- 2018
4. Evaluation of impact of land use and landscape metrics on surface water quality in the northeastern part along Lake Tanganyika, Africa.
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Yu, Cheng, Xia, Shiyu, Chen, Sofia Shuang, Gao, Qun, Wang, Zhaode, Shen, Qiushi, and Kimirei, Ismael Aaron
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WATER quality ,WATER quality monitoring ,LAND use ,FRAGMENTED landscapes ,MUNICIPAL water supply ,LAKES ,WATERSHEDS - Abstract
As the second deepest lake in Africa, Lake Tanganyika plays an important role in supplying fish protein for the catchment's residents and is irreplaceable in global biodiversity. However, the lake's water environment is threatened by socioeconomic development and rapid population growth along the lake. This study analyzed the spatial scale effects and seasonal dependence of land use types and landscape metrics on water quality in 16 sub-basins along northeastern Lake Tanganyika at different levels of urbanization. The results revealed that land use types had a higher influence on water quality in urban areas than that in rural areas; the explanatory variance in the urban area was 0.78–0.96, while it was 0.21–0.70 in the rural area. The explanatory ability of land use types on water quality was better at the buffer scale than at the sub-watershed scale, and the 500 m buffer scale had the highest explanatory ability in the urban area and rural area both in the rainy season and dry season, and artificial surface and arable land were the main contributing factors. And this phenomenon was more obvious in dry season than in rainy season. We identified that CONTAG was the key landscape metric in urban area and was positively correlated with nutrient variables, indicating that water quality degraded in less fragmented landscapes. The sub-watershed scale had the highest explained ability, while in rural area, the 1500 m buffer scale had the highest explained ability and IJI had the highest explanatory variance, which had a negative effect on water quality. Research on the relationship between land use and water quality would help assess the water quality in the unmonitored watershed as monitoring is expensive and time-consuming in low-income area. This knowledge would provide guideline to watershed managers and policymakers to prioritize the future land use development within Lake Tanganyika basin. [ABSTRACT FROM AUTHOR]
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- 2024
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5. Association between light at night and the risk of child death in sub-saharan Africa: a cross-sectional analysis based on DHS data.
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Li, Xinyue, Bachwenkizi, Jovine, Chen, Renjie, Kan, Haidong, and Meng, Xia
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CHILD death ,DEMOGRAPHIC surveys ,PROPORTIONAL hazards models ,CROSS-sectional method ,CHILD mortality - Abstract
Background: The high under-five mortality rate (U5MR) in Africa is a significant public health concern. Previous studies have found that satellite retrieved light at night (LAN) data with long-term and global coverage can be used as a proxy for socio-economic development and urbanization. Currently, few studies on the effects of LAN on child mortality have been conducted in Africa, a region with varying levels of urbanization between countries. Objective: To quantify the correlation between risk of child mortality and LAN as an indicator of urbanization and economic development in Africa. Methods: Using data from the Demographic and Health Survey (DHS) database conducted in 15 African countries out of 46 countries from 2005 to 2013, this study estimated LAN levels for children based on their year of birth and residential addresses. This study used Cox proportional hazards models to assess the association between LAN and the risk of child mortality in Africa. Results: The mean U5MR was 95 per 1,000 livebirths among the 15 African countries during 2005–2013. After adjusting for covariates, each 10-unit increment in LAN was associated with a 5.3% reduction in the risk of U5MR. The effect estimates were more pronounced in areas with lower LAN. Conclusion: In Africa, the risk of U5MR decreased with increasing LAN, especially in areas with lower LAN. The results suggest that the development of urbanization and socio-economic conditions may be beneficial to child health, especially in regions with low LAN. The use of LAN as a proxy may offer an intriguing approach for identifying areas requiring targeted development in urbanization and socio-economic conditions. [ABSTRACT FROM AUTHOR]
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- 2023
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6. Typification of Adanson's generic name Pacoseroca (Zingiberaceae) and its implications.
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Bai, Lin, Leong‐Škorničková, Jana, and Xia, Nianhe
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ZINGIBERACEAE ,ALPINIA ,ZINGIBER ,SPECIES ,SYNONYMS - Abstract
Since its publication by Adanson in 1763, the name Pacoseroca has been treated as a synonym of several genera of Zingiberaceae by different authors. It is currently treated as a homotypic synonym of Zingiber Mill. (≡ Amomum L., nom. rej.) in Index Nominum Genericorum. No binomial combination has ever been proposed in Pacoseroca, and the typification of this long‐forgotten generic name has never been undertaken. We show here that Pacoseroca is not homotypic with Amomum L. Instead, its protologue included elements that belong to at least three rather distantly related genera of Zingiberaceae (Aframomum, Elettaria, Renealmia), over all of which Pacoseroca has priority. Based on a study of the protologue and of Adanson's working methods, we typify Pacoseroca with Renealmia alpinia (Rottb.) Maas (≡ Amomum alpinia Rottb.), a species which is the best fit to a plant recorded by Marcgrave under the vernacular name "Paco seroca" and upon which Adanson based his generic name. A formal proposal to reject Pacoseroca will be submitted to uphold the well‐known Renealmia and to prevent new combinations for 82 species names currently accepted in this genus, which is widespread in Africa and South America. [ABSTRACT FROM AUTHOR]
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- 2023
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7. The Spread of New Chinese Socialist Martial Arts Films in Africa.
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Zhang, Yong and Xia, Yiwen
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CHINESE martial arts , *CHINESE films , *ATTITUDE change (Psychology) , *AFRICA-China relations , *ECONOMIC reform ,DEVELOPING countries - Abstract
In the 1970s, Hong Kong kung fu films were distributed across Africa and reached large audiences. Although the spread of Hong Kong films in Africa has received some scholarly attention worldwide, the African reception of Chinese films in the post-Mao era has rarely been analysed. Based on archival research and the collation of historical data and materials, this article discusses the background and advancement of the new Chinese socialist martial arts films across Africa and uses the acclaimed film Wudang as a case study to explore the spread of Chinese socialist martial arts films. This article argues that Mainland Chinese films' imitation of Hong Kong films was a strategic choice made in the context of the Economic Reform and Opening Up policies, in response to Africans' changing attitudes toward socialist ideology. The research contributes to the understanding of the historical exchanges between China and Africa in the post-Mao era, as well as to the topic of cooperation in the Global South today. [ABSTRACT FROM AUTHOR]
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- 2022
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8. Could China's journey of malaria elimination extend to Africa?
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Wang, Duoquan, Lv, Shan, Ding, Wei, Lu, Shenning, Zhang, Hongwei, Kassegne, Kokouvi, Xia, Shang, Duan, Lei, Ma, Xuejiao, Huang, Lulu, Gosling, Roly, Levens, Joshua, Abdulla, Salim, Mudenda, Mutinta, Okpeku, Moses, Matengu, Kenneth Kamwi, Serge Diagbouga, Potiandi, Xiao, Ning, and Zhou, Xiao-Nong
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MALARIA ,MALARIA prevention ,AFRICA-China relations ,ARTEMISININ - Abstract
World Health Organization (WHO) certified China malaria-free on June 30, 2021, which brightens the goal of global malaria elimination efforts. China contributed its unique innovations to the global community: Artemisinin, discovered by Tu Youyou, has saved millions of lives globally; the "1-3-7" norm developed in 2012, has been adapted in the local contexts of countries in the Southeast Asia and Africa. How to the targets of Global Technical Strategy for Malaria (GTS) 2016−2030. By looking into the malaria control phase, towards elimination phase from 1960 to 2011 in sub-Saharan Africa and China, we found that the gap in malaria burden will widen unless the interventions in Africa are enhanced. It is imperative to identify the key China–Africa cooperation areas on malaria control and elimination, so that synergized efforts could be pooled together to help African countries achieve the elimination goal. The practices from China malaria control and elimination efforts could be leveraged to fast-track malaria elimination efforts in Africa, which makes it possible that the China's journey of malaria elimination extends to Africa. [ABSTRACT FROM AUTHOR]
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- 2022
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9. Assessing the impacts of agricultural managements on soil carbon stocks, nitrogen loss, and crop production – a modelling study in eastern Africa.
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Ma, Jianyong, Rabin, Sam S., Anthoni, Peter, Bayer, Anita D., Nyawira, Sylvia S., Olin, Stefan, Xia, Longlong, and Arneth, Almut
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AGRICULTURAL productivity ,SOIL management ,NO-tillage ,CARBON in soils ,COVER crops ,CROP yields ,ENVIRONMENTAL economics ,SOIL dynamics - Abstract
Improved agricultural management plays a vital role in protecting soils from degradation in eastern Africa. Changing practices such as reducing tillage, fertilizer use, or cover crops are expected to enhance soil organic carbon (SOC) storage, with climate change mitigation co-benefits, while increasing crop production. However, the quantification of cropland management effects on agricultural ecosystems remains inadequate in this region. Here, we explored seven management practices and their potential effects on soil carbon (C) pools, nitrogen (N) losses, and crop yields under different climate scenarios, using the dynamic vegetation model LPJ-GUESS. The model performance is evaluated against observations from two long-term maize field trials in western Kenya and reported estimates from published sources. LPJ-GUESS generally produces soil C stocks and maize productivity comparable with measurements and mostly captures the SOC decline under some management practices that is observed in the field experiments. We found that for large parts of Kenya and Ethiopia, an integrated conservation agriculture practice (no-tillage, residue and manure application, and cover crops) increases SOC levels in the long term (+11 % on average), accompanied by increased crop yields (+22 %) in comparison to the conventional management. Planting nitrogen-fixing cover crops in our simulations is also identified as a promising individual practice in eastern Africa to increase soil C storage (+4 %) and crop production (+18 %), with low environmental cost of N losses (+24 %). These management impacts are also sustained in simulations of three future climate pathways. This study highlights the possibilities of conservation agriculture when targeting long-term environmental sustainability and food security in crop ecosystems, particularly for those with poor soil conditions in tropical climates. [ABSTRACT FROM AUTHOR]
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- 2022
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10. onset of deep recycling of supracrustal materials at the Paleo-Mesoarchean boundary.
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Wang, Xiaolei, Tang, Ming, Moyen, Jeff, Wang, Di, Kröner, Alfred, Hawkesworth, Chris, Xia, Xiaoping, Xie, Hangqiang, Anhaeusser, Carl, Hofmann, Axel, Li, Junyong, and Li, Linsen
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INTERNAL structure of the Earth ,SURFACE of the earth ,OCEANIC crust ,PLATE tectonics ,CONTINENTAL crust ,LASER ablation inductively coupled plasma mass spectrometry - Abstract
The recycling of supracrustal materials, and in particular hydrated rocks, has a profound impact on mantle composition and thus on the formation of continental crust, because water modifies the physical properties of lithological systems and the mechanisms of partial melting and fractional fractionation. On the modern Earth, plate tectonics offers an efficient mechanism for mass transport from the Earth's surface to its interior, but how far this mechanism dates back in the Earth's history is still uncertain. Here, we use zircon oxygen (O) isotopes to track recycling of supracrustal materials into the magma sources of early Archean igneous suites from the Kaapvaal Craton, southern Africa. The mean δ
18 O values of zircon from TTG (tonalite–trondhjemite–granodiorite) rocks abruptly increase at the Paleo-Mesoarchean boundary (ca. 3230 million years ago; Ma), from mantle zircon values of 5‰–6‰ to approaching 7.1‰, and this increase occurs in ≤3230 Ma rocks with elevated Dy/Yb ratios. The18 O enrichment is a unique signature of low-temperature water–rock interaction on the Earth's surface. Because the later phase was emplaced into the same crustal level as the older one and TTG magmas would derive from melting processes in the garnet stability field (>40 km depth), we suggest that this evident shift in TTG zircon O isotopic compositions records the onset of recycling of the mafic oceanic crust that underwent seawater hydrothermal alteration at low temperature. The onset of the enhanced recycling of supracrustal materials may also have developed elsewhere in other Archean cratons and reflects a significant change in the tectonic realm during craton formation and stabilization, which may be important processes for the operation of plate tectonics on early Earth. [ABSTRACT FROM AUTHOR]- Published
- 2022
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11. Larval sites of the mosquito Aedes aegypti formosus in forest and domestic habitats in Africa and the potential association with oviposition evolution.
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Siyang Xia, Dweck, Hany K. M., Lutomiah, Joel, Sang, Rosemary, McBride, Carolyn S., Rose, Noah H., Ayala, Diego, and Powell, Jeffrey R.
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OVIPARITY , *AEDES aegypti , *HABITATS , *ARBOVIRUS diseases , *MOSQUITOES , *TREE cavities , *HUMAN settlements - Abstract
Adaptations to anthropogenic domestic habitats contribute to the success of the mosquito Aedes aegypti as a major global vector of several arboviral diseases. The species inhabited African forests before expanding into domestic habitats and spreading to other continents. Despite a well-studied evolutionary history, how this species initially moved into human settlements in Africa remains unclear. During this initial habitat transition, African Ae. aegypti switched their larval sites from natural water containers like tree holes to artificial containers like clay pots. Little is known about how these natural versus artificial containers differ in their characteristics. Filling this knowledge gap could provide valuable information for studying the evolution of Ae. aegypti associated with larval habitat changes. As an initial effort, in this study, we characterized the microenvironments of Ae. aegypti larval sites in forest and domestic habitats in two African localities: La Lopé, Gabon, and Rabai, Kenya. Specifically, we measured the physical characteristics, microbial density, bacterial composition, and volatile chemical profiles of multiple larval sites. In both localities, comparisons between natural containers in the forests and artificial containers in the villages revealed significantly different microenvironments. We next examined whether the between-habitat differences in larval site microenvironments lead to differences in oviposition, a key behavior affecting larval distribution. Forest Ae. aegypti readily accepted the artificial containers we placed in the forests. Laboratory choice experiments also did not find distinct oviposition preferences between forest and village Ae. aegypti colonies. These results suggested that African Ae. aegypti are likely generalists in their larval site choices. This flexibility to accept various containers with a wide range of physical, microbial, and chemical conditions might allow Ae. aegypti to use human-stored water as fallback larval sites during dry seasons, which is hypothesized to have initiated the domestic evolution of Ae. aegypti. [ABSTRACT FROM AUTHOR]
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- 2021
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12. High Frequency Mutations in pfdhfr and pfdhps of Plasmodium falciparum in Response to Sulfadoxine-Pyrimethamine: A Cross-Sectional Survey in Returning Chinese Migrants From Africa.
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Yan, He, Feng, Jun, Yin, Jian-hai, Huang, Fang, Kong, Xiang-li, Lin, Kang-ming, Zhang, Tao, Feng, Xin-yu, Zhou, Shui-sen, Cao, Jian-ping, and Xia, Zhi-gui
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PLASMODIUM falciparum ,SINGLE nucleotide polymorphisms ,RETURN migrants ,TETRAHYDROFOLATE dehydrogenase ,MALARIA ,MIGRANT labor - Abstract
Background: Sulfadoxine-pyrimethamine (SP) is recommended for intermittent preventive treatment in Africa against Plasmodium falciparum infection. However, increasing SP resistance (SPR) of P. falciparum affects the therapeutic efficacy of SP, and pfdhfr (encoding dihydrofolate reductase) and pfdhps (encoding dihydropteroate synthase) genes are widely used as molecular markers for SPR surveillance. In the present study, we analyzed single nucleotide polymorphisms (SNPs) of pfdhfr and pfdhps in P. falciparum isolated from infected Chinese migrant workers returning from Africa. Methods: In total, 159 blood samples from P. falciparum -infected workers who had returned from Africa to Anhui, Shangdong, and Guangxi provinces were successfully detected and analyzed from 2017 to 2019. The SNPs in pfdhfr and pfdhps were analyzed using nested PCR. The genotypes and linkage disequilibrium (LD) were analyzed using Haploview. Results: High frequencies of the Asn51Ile (N51I), Cys59Arg(C59R), and Ser108Asn(S108N) mutant alleles were observed, with mutation frequencies of 97.60, 87.43, and 97.01% in pfdhfr , respectively. A triple mutation (IRN) in pfdhfr was the most prevalent haplotype (86.83%). Six point mutations were detected in pfdhps DNA fragment, Ile431Val (I431V), Ser436Ala (S436A), Ala437Gly (A437G), Lys540Glu(K540E), Ala581Gly(A581G), Ala613Ser(A613S). The pfdhps K540E (27.67%) was the most predominant allele, followed by S436A (27.04%), and a single mutant haplotype (SGKAA; 62.66%) was predominant in pfdhps. In total, 5 haplotypes of the pfdhfr gene and 13 haplotypes of the pfdhps gene were identified. A total of 130 isolates with 12 unique haplotypes were found in the pfdhfr-pfdhps combined haplotypes, most of them (n = 85, 65.38%) carried quadruple allele combinations (CIRNI-SGKAA). Conclusion: A high prevalence of point mutations in the pfdhfr and pfdhps genes of P. falciparum isolates was detected among Chinese migrant workers returning from Africa. Therefore, continuous in vitro molecular monitoring of Sulfadoxine-Pyrimethemine combined in vivo therapeutic monitoring of artemisinin combination therapy (ACT) efficacy and additional control efforts among migrant workers are urgently needed. [ABSTRACT FROM AUTHOR]
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- 2021
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13. Genetic Diversity Analysis of Surface-Related Antigen (SRA) in Plasmodium falciparum Imported From Africa to China.
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Yang, Bo, Liu, Hong, Xu, Qin-Wen, Sun, Yi-Fan, Xu, Sui, Zhang, Hao, Tang, Jian-Xia, Zhu, Guo-Ding, Liu, Yao-Bao, Cao, Jun, and Cheng, Yang
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GENETIC variation ,PLASMODIUM falciparum ,GENETIC polymorphisms ,ANTIGENS ,VACCINE effectiveness ,COVID-19 ,MALARIA - Abstract
Plasmodium falciparum surface-related antigen (SRA) is located on the surfaces of gametocyte and merozoite and has the structural and functional characteristics of potential targets for multistage vaccine development. However, little information is available regarding the genetic polymorphism of pfsra. To determine the extent of genetic variation about P. falciparum by characterizing the sra sequence, 74 P. falciparum samples were collected from migrant workers who returned to China from 12 countries of Africa between 2015 and 2019. The full length of the sra gene was amplified and sequenced. The average pairwise nucleotide diversities (π) of P. falciparum sra gene was 0.00132, and the haplotype diversity (Hd) was 0.770. The average number of nucleotide differences (k) for pfsra was 3.049. The ratio of non-synonymous (dN) to synonymous (dS) substitutions across sites (dN / dS) was 1.365. Amino acid substitutions of P. falciparum SRA could be categorized into 35 unique amino acid variants. Neutrality tests showed that the polymorphism of PfSRA was maintained by positive diversifying selection, which indicated its role as a potential target of protective immune responses and a vaccine candidate. Overall, the ability of the N-terminal of PfSRA antibodies to evoke inhibition of merozoite invasion of erythrocytes and conserved amino acid at low genetic diversity suggest that the N-terminal of PfSRA could be evaluated as a vaccine candidate against P. falciparum infection. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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14. Molecular surveillance of pfcrt, pfmdr1 and pfk13-propeller mutations in Plasmodium falciparum isolates imported from Africa to China.
- Author
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Huang, Fang, Yan, He, Xue, Jing-Bo, Cui, Yan-Wen, Zhou, Shui-Sen, Xia, Zhi-Gui, Abeyasinghe, Rabindra, Ringwald, Pascal, and Zhou, Xiao-Nong
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PLASMODIUM falciparum ,DRIED blood spot testing ,FISHER exact test ,MULTIDRUG resistance ,DRUG resistance - Abstract
Background: The emergence and spread of multidrug resistance poses a significant risk to malaria control and eradication goals in the world. There has been no indigenous malaria cases reported in China since 2017, and China is approaching national malaria elimination. Therefore, anti-malarial drug resistance surveillance and tracking the emergence and spread of imported drug-resistant malaria cases will be necessary in a post-elimination phase in China. Methods: Dried blood spots were obtained from Plasmodium falciparum-infected cases returned from Africa to China between 2012 and 2015, prior to anti-malarial drug treatment. Whole DNA were extracted and known polymorphisms relating to drug resistance of pfcrt, pfmdr1 gene, and the propeller domain of pfk13 were evaluated by nested PCR and sequencing. The haplotypes and prevalence of these three genes were evaluated separately. Chi-squared test and Fisher's exact test were used to evaluate differences among the different sub-regions of Africa. A P value < 0.05 was used to evaluate differences with statistical significance. The maps were created using ArcGIS. Results: A total of 731 P. falciparum isolates were sequenced at the pfcrt locus. The wild type CVMNK was the most prevalent haplotype with prevalence of 62.8% and 29.8% of the isolates showed the triple mutant haplotype CVIET. A total of 434 P. falciparum isolates were successfully sequenced and pfmdr1 allelic variants were observed in only codons 86, 184 and 1246. Twelve haplotypes were identified and the prevalence of the wild type pfmdr1 NYD was 44.1%. The single mutant pfmdr1 in codons 86 and 184 was predominant but the haplotype NYY with single mutation in codon 1246 was not observed. The double mutant haplotype YFD was common in Africa. About 1,357 isolates were successfully sequenced of pfk13-propeller domain, the wild type was found in 1,308 samples (96.4%) whereby 49 samples (3.6%) had mutation in pfk13. Of 49 samples with pfk13 mutations, 22 non-synonymous and 4 synonymous polymorphic sites were confirmed. The A578S was the most common mutation in pfk13-propeller domain and three mutations associated with artemisinin resistance (M476I, R539T, P553L) were identified in three isolates. Conclusion: This study provides evidence that could give insight into potential issues with anti-malarial drug resistance to inform national drug policy in China in order to treat imported cases. [ABSTRACT FROM AUTHOR]
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- 2021
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15. Potentials of marine natural products against malaria, leishmaniasis, and trypanosomiasis parasites: a review of recent articles.
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Nweze, Justus Amuche, Mbaoji, Florence N., Li, Yan-Ming, Yang, Li-Yan, Huang, Shu-Shi, Chigor, Vincent N., Eze, Emmanuel A., Pan, Li-Xia, Zhang, Ting, and Yang, Deng-Feng
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MARINE natural products ,TRYPANOSOMIASIS ,LEISHMANIASIS ,MALARIA ,PARASITIC diseases - Abstract
Background: Malaria and neglected communicable protozoa parasitic diseases, such as leishmaniasis, and trypanosomiasis, are among the otherwise called diseases for neglected communities, which are habitual in underprivileged populations in developing tropical and subtropical regions of Africa, Asia, and the Americas. Some of the currently available therapeutic drugs have some limitations such as toxicity and questionable efficacy and long treatment period, which have encouraged resistance. These have prompted many researchers to focus on finding new drugs that are safe, effective, and affordable from marine environments. The aim of this review was to show the diversity, structural scaffolds, in-vitro or in-vivo efficacy, and recent progress made in the discovery/isolation of marine natural products (MNPs) with potent bioactivity against malaria, leishmaniasis, and trypanosomiasis. Main text: We searched PubMed and Google scholar using Boolean Operators (AND, OR, and NOT) and the combination of related terms for articles on marine natural products (MNPs) discovery published only in English language from January 2016 to June 2020. Twenty nine articles reported the isolation, identification and antiparasitic activity of the isolated compounds from marine environment. A total of 125 compounds were reported to have been isolated, out of which 45 were newly isolated compounds. These compounds were all isolated from bacteria, a fungus, sponges, algae, a bryozoan, cnidarians and soft corals. In recent years, great progress is being made on anti-malarial drug discovery from marine organisms with the isolation of these potent compounds. Comparably, some of these promising antikinetoplastid MNPs have potency better or similar to conventional drugs and could be developed as both antileishmanial and antitrypanosomal drugs. However, very few of these MNPs have a pharmaceutical destiny due to lack of the following: sustainable production of the bioactive compounds, standard efficient screening methods, knowledge of the mechanism of action, partnerships between researchers and pharmaceutical industries. Conclusions: It is crystal clear that marine organisms are a rich source of antiparasitic compounds, such as alkaloids, terpenoids, peptides, polyketides, terpene, coumarins, steroids, fatty acid derivatives, and lactones. The current and future technological innovation in natural products drug discovery will bolster the drug armamentarium for malaria and neglected tropical diseases. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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16. Genetic diversity of Plasmodium falciparum and genetic profile in children affected by uncomplicated malaria in Cameroon.
- Author
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Metoh, Theresia Njuabe, Chen, Jun-Hu, Fon-Gah, Philip, Zhou, Xia, Moyou-Somo, Roger, and Zhou, Xiao-Nong
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PLASMODIUM falciparum ,MALARIA ,GENETIC markers ,RANDOMIZED controlled trials ,NUCLEOTIDE sequence ,GENETIC profile - Abstract
Background: Malaria is a major public health problem in Cameroon. The study of the genetic diversity within parasite population is essential for understanding the mechanism underlying malaria pathology and to determine parasite clones profile in an infection, for proper malaria control strategies. The objective of this study was to perform a molecular characterization of highly polymorphic genetic markers of Plasmodium falciparum, and to determine allelic distribution with their influencing factors valuable to investigate malaria transmission dynamics in Cameroon. Methods: A total of 350 P. falciparum clinical isolates were characterized by genotyping block 2 of msp-1, block 3 of msp-2, and region II of glurp gene using nested PCR and DNA sequencing between 2012 and 2013. Results: A total of 5 different genotypes with fragment sizes ranging from 597 to 817 bp were recorded for GLURP. Overall, 16 MSP-1 genotypes, including K1, MAD20 and RO33 were identified, ranging from 153 to 335 bp. A peculiarity about this study is the RO33 monomorphic pattern revealed among the Pfmsp-1 allelic type. Again, this study identified 27 different Pfmsp-2 genotypes, ranging from 140 to 568 bp in size, including 15 belonging to the 3D7-type and 12 to the FC27 allelic families. The analysis of the MSP-1 and MSP-2 peptides indicates that the region of the alignment corresponding K1 polymorphism had the highest similarity in the MSP1and MSP2 clade followed by MAD20 with 93% to 100% homology. Therefore, population structure of P. falciparum isolates is identical to that of other areas in Africa, suggesting that vaccine developed with K1 and MAD20 of Pfmsp1 allelic variant could be protective for Africa children but these findings requires further genetic and immunological investigations. The multiplicity of infection (MOI) was significantly higher (P < 0.05) for Pfmsp-2 loci (3.82), as compare with Pfmsp-1 (2.51) and heterozygotes ranged from 0.55 for Pfmsp-1 to 0.96 for Pfmsp-2. Conclusion: High genetic diversity and allelic frequencies in P. falciparum isolates indicate a persisting high level of transmission. This study advocate for an intensification of the malaria control strategies in Cameroon. Trial registration This study was approved by Cameroon National Ethics Committee. It is a randomized controlled trial retrospectively registered in NIH U.S. National Library of Medicine, ClinicalTrials.gov on the 28/11/2016 at https://clinicaltrials.gov/ct2/show/NCT02974348 with the registration number NCT02974348 [ABSTRACT FROM AUTHOR]
- Published
- 2020
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17. Molecular Evidence of Human Monkeypox Virus Infection, Sierra Leone.
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Fei Ye, Jingdong Song, Li Zhao, Yi Zhang, Lianxu Xia, Lingwei Zhu, Kamara, Idrissa Laybohr, Jiao Ren, Wenling Wang, Houwen Tian, Guizhen Wu, Wenjie Tan, Ye, Fei, Song, Jingdong, Zhao, Li, Zhang, Yi, Xia, Lianxu, Zhu, Lingwei, Ren, Jiao, and Wang, Wenling
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VIRUS diseases ,ZOONOSES ,ENDEMIC diseases ,ANIMALS ,SEQUENCE analysis - Abstract
Monkeypox virus is a zoonotic disease endemic to Africa. In 2017, we confirmed a case of human monkeypox virus in Sierra Leone by molecular and serologic methods. Sequencing analysis indicated the virus belongs to the West African clade and data suggest it was likely transmitted by wild animals. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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18. Next-generation Sequencing Study of Pathogens in Serum from Patients with Febrile Jaundice in Sierra Leone.
- Author
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ZHANG, Yi, YE, Fei, XIA, Lian Xu, ZHU, Ling Wei, IDRISSA, Laybohr Kamara, HUANG, Ke Qiang, ZHANG, Yong, LIU, Jun, BRIMA, Kargbo, WANG, Ji, LIANG, Mi Fang, SONG, Jing Dong, MA, Xue Jun, and WU, Gui Zhen
- Subjects
EBOLA virus ,HEPATITIS E virus ,JAUNDICE ,HEPATITIS C virus ,HEPATITIS B virus ,PATHOGENIC microorganisms - Abstract
People in Western Africa suffer greatly from febrile jaundice, which is caused by a variety of pathogens. However, yellow fever virus (YFV) is the only pathogen under surveillance in Sierra Leone owing to the undeveloped medical and public health system there. Most of the results of YFV identification are negative. Elucidation of the pathogen spectrum is required to reduce the prevalence of febrile jaundice. In the present study, we used Ion Torrent semiconductor sequencing to profile the pathogen spectrum in archived YFV-negative sera from 96 patients in Sierra Leone who presented with unexplained febrile jaundice. The most frequently identified sequencing reads belonged to the following pathogens: cytomegalovirus (89.58%), Epstein-Barr virus (55.21%), hepatitis C virus (34.38%), rhinovirus (28.13%), hepatitis A virus (20.83%), coxsackievirus (10.42%), Ebola virus (8.33%), hepatitis E virus (8.33%), lyssavirus (4.17%), leptospirosis (4.17%), chikungunya virus (2.08%), Crimean-Congo hemorrhagic fever virus (1.04%), and hepatitis B virus (1.04%). The distribution of sequencing reads suggests a broader spectrum of pathogens for consideration in clinical diagnostics and epidemiological surveillance in Sierra Leone. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
19. THE INTERDECADAL VARIATION OF THE SOUTH ASIAN HIGH AND ITS ASSOCIATION WITH THE SEA SURFACE TEMPERATURE OF TROPICAL AND SUBTROPICAL REGIONS.
- Author
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Li-xia PENG, Wei-jun ZHU, Zhong-xian LI, Dong-hong NI, Hai-shan CHEN, Lin-lin PAN, and Yu-bao LIU
- Subjects
- *
OCEAN temperature , *SOUTH Asians , *GENERAL circulation model , *CYCLONES - Abstract
This study aims to explore the interdecadal variation of South Asian High (SAH) and its relationship with SST (Sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis data from 1948 to 2012, based on the NCAR CAM 3.0 general circulation model. The results show that: 1) the intensity of SAH represents a remarkable interdecadal variation characteristic, the intensity of SAH experienced from weak to strong at the late 1970s, and after the late 1970s, its strength is enhanced and the area is expanded in the east-west direction. The expansion degree is greater westward than eastward, while it is opposite in summer. 2) Corresponding to the interdecadal variation of SAH intensity, after the late 1970s, the divergent component of wind field has two ascending and three descending areas. Of the two ascending areas, one is located in the East Pacific, the other location varies with the season from the Indian Ocean in winter to the South China Sea and West Pacific in summer. Three descending areas are located in the north-central Africa, the East Asia and the Middle Pacific region respectively. 3) Corresponding to the interdecadal variation of SAH intensity, the rotational component of wind field at the lower level is an anomalous cyclone over the South China Sea and West Pacific in summer, while in winter, it is an anomalous cyclone over the Indian Ocean, and an anomalous anticyclone over the equatorial Middle Pacific. 4) Numerical simulations show that the interdecadal variation of SAH is closely related to the SST of the tropical and subtropical regions. The SST of Indian Ocean plays an important role in winter, while in summer, the SST of the South China Sea and West Pacific plays an important role, and the SST of the East Pacific also plays a certain role. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
20. Psychological maladjustment of Asian and African peacekeepers in Liberia and its related factors.
- Author
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Chen, Sheng-dong, Sun, Xin-yang, Zhang, Li-yi, Kong, Ling-ming, Chen, Li-ji, Guo, Jian, Lin, Hai, Chen, Chun-xia, and Yao, Gao-feng
- Subjects
INDUSTRIAL safety & psychology ,ANALYSIS of variance ,BEHAVIOR ,REGRESSION analysis ,MILITARY personnel ,SOCIAL support ,WELL-being ,DATA analysis software ,DESCRIPTIVE statistics ,CLUSTER sampling - Abstract
This study aimed to investigate the maladjustment of Asian (Bangladeshi, Pakistani) and African (Nigerian, Namibian, Ghanaian) peacekeepers and its major influence factors. By random cluster sampling, 300 Asian peacekeepers and 271 African peacekeepers were administered the military psychological maladjustment scale (MPMS) and risk factors questionnaire. Investigation at Day 7 and Day 120 into the peacekeeping deployment period indicated that MPMS total score and factor scores of the Asian peacekeepers were significantly lower than those of the African peacekeepers (p < .01). The total score and each factor score of MPMS of the Asian peacekeepers significantly decreased (p < .01); for the African peacekeepers, only the factor score of emotional disorder of MPMS significantly decreased (p < .05). Stepwise regression analysis showed that the education duration was the influence factor for the emotional disorder factor score in the Asian peacekeepers, and the two factors were positively correlated. Age, military service duration, education duration and marital status were the major influence factors for the MPMS factors of the African peacekeepers, among which age was negatively correlated with the total score and each factor score, and military service duration, education duration and marital status were positively related. We conclude that the Asian peacekeepers are more adaptable and resilient than the African peacekeepers. Education duration was the major influence factor for Emotional Disorder in the Asian peacekeepers. The major influence factors for maladjustment in the African peacekeepers were age, military service duration, education duration and marital status. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
21. The Janus face of stateness: China's development-oriented equity investments in Africa.
- Author
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Xia, Ying and Chen, Muyang
- Subjects
- *
INVESTMENTS , *INVESTORS , *DEVELOPMENT credit corporations - Abstract
• In the post-financial crisis era, fiscal challenges have led countries adopt a more market-based means of development finance. • The state is not a sheer subsidizer distorting market in favor of policy objectives, but a risk-sharing, profit-seeking equity investor. • China's investment fund offers not only equity shares but also state-related resources to assist private firms' business expansion in Africa. • Stateness has prevented the investment fund from choosing the most financially promising projects or withdrawing from the failing ones. The post-2008 financial crisis era has witnessed a significant change in the global development landscape. Fiscal challenges have led countries that historically provided state-led, gift-like development assistance to adopt a more market-based means of development finance driven by self-interest. This allows us to reconsider the roles of the state and the market in development by focusing on the China-Africa Development Fund (CADFund), China's first official development-oriented investment fund and a subsidiary of the China Development Bank, the world's largest national development bank. This paper draws from interviews and participant observations involving CADFund, its partners, and project companies in Africa to examine how China's official finance mobilizes private investment to facilitate global development. The findings indicate that the state-led equity fund has catalyzed the start-up and expansion of Chinese overseas private enterprises by providing otherwise inaccessible equity support and channeling additional state-related resources to empower long-term business development. Meanwhile, stateness has created an adverse selection problem, preventing CADFund from choosing the most financially promising projects or withdrawing from the failing ones. The paper sheds light on the potential challenges facing development finance institutions in employing equity investment as a tool for reconciling long-term development objectives and short-term commercial objectives. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
22. Prevalence of Budd-Chiari Syndrome during Pregnancy or Puerperium: A Systematic Review and Meta-Analysis.
- Author
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Ren, Weirong, Li, Xiang, Jia, Jia, Xia, Yan, Hu, Fengrong, and Xu, Zhengyu
- Subjects
HEPATIC veins ,DISEASE prevalence ,PUERPERIUM ,SYSTEMATIC reviews ,META-analysis ,DISEASES ,PHYSIOLOGY - Abstract
Women during pregnancy or puerperium are likely to develop Budd-Chiari syndrome (BCS). However, the reported prevalence of pregnancy-related BCS varied considerably among studies. Our study aims to systematically review this issue. Overall, 817 papers were initially identified via the PubMed, EMBASE, China National Knowledge Infrastructure, and Chinese Scientific and Technological Journal databases. Twenty of them were eligible. The prevalence of pregnancy-related BCS varied from 0% to 21.5%. The pooled prevalence was 6.8% (95% CI: 3.9–10.5%) in all BCS patients, 6.3% (95% CI: 3.8–9.4%) in primary BCS patients, and 13.1% (95% CI: 7.1–20.7%) in female BCS patients. Among them, one study was carried out in Africa with a prevalence of 10.6%; 14 studies in Asian countries with a pooled prevalence of 7.1% (95% CI: 3.1–12.6%); and 5 studies in European countries with a pooled prevalence of 5.0% (95% CI: 3.1–7.3%). The pooled prevalence was 6.7% (95% CI: 2.6–12.3%) in studies published before 2005 and 7.3% (95% CI: 4.2–12.5%) in those published after 2005. In conclusion, pregnancy is a relatively common risk factor for BCS, but there is a huge variation in the prevalence among studies. Physicians should be aware of pregnancy-related BCS. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
23. Systematic evaluation of cancer risk associated with DNMT3B polymorphisms.
- Author
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Duan, Fujiao, Cui, Shuli, Song, Chunhua, Dai, Liping, Zhao, Xia, and Zhang, Xiaoqin
- Subjects
CANCER risk factors ,DNA methyltransferases ,GENETIC polymorphisms ,ODDS ratio ,POPULATION biology - Abstract
Purpose: The aim of our study is to provide a precise quantification for the association between DNA methyltransferase 3B (DNMT3B) variations (rs2424913 C/T, rs1569686 G/T, rs6087990 T/C and rs2424908 T/C) and the risk of cancer. Methods: We performed a systematic literature review and assessed the methodological quality of included case-control designed studies based on Newcastle-Ottawa Scale. Pooled odds ratios (ORs) and corresponding 95 % confidence intervals (95 % CIs) were calculated to assess the strengths of the associations. Results: We identified 34 studies for pooled analyses. Overall, the results demonstrated that rs2424913 polymorphism was significantly associated with negative cancer risk in the African population (CT vs TT: OR 0.10, 95 % CI 0.02-0.63, P = 0.01; CT+CC vs TT: OR 0.14, 95 % CI 0.03-0.76, P = 0.02), and the rs1569686 polymorphism was significantly associated with a subtly decreased cancer risk (GT vs TT: OR 0.80, 95 % CI 0.72-0.90, P < 0.01; GT+GG vs TT: OR 0.84, 95 % CI 0.76-0.94, P < 0.01), particularly in the Asian population (GT vs TT: OR 0.79, 95 % CI 0.66-0.96, P < 0.01) and in colorectal cancer subgroup (G vs T: OR 0.69, 95 % CI 0.54-0.88, P < 0.01). In addition, the rs6087990 polymorphism was associated with decreased risk in Asian population (T vs C: OR 0.77, 95 % CI 0.62-0.96, P = 0.02). Similarly, the rs2424908 polymorphism was observed as a protective factor for cancer in the Asian population (CT+CC vs TT: OR 0.79, 95 % CI 0.66-0.95, P = 0.01). Conclusions: DNMT3B polymorphisms might be associated with decreased cancer risk especially in the Asian population and for colorectal cancer. Further multicentric studies are still needed to confirm the results. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
24. Chapter Twelve - China-Africa Cooperation Initiatives in Malaria Control and Elimination.
- Author
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Zhi-Gui Xia, Ru-Bo Wang, Duo-Quan Wang, Jun Feng, Qi Zheng, Chang-Sheng Deng, Abdulla, Salim, Ya-Yi Guan, Wei Ding, Jia-Wen Yao, Ying-Jun Qian, Bosman, Andrea, Newman, Robert David, Ernest, Tambo, O'leary, Michael, and Ning Xiao
- Subjects
- *
MALARIA prevention , *SOCIAL development , *ECONOMIC development , *PUBLIC health , *PRIMARY health care - Abstract
Malaria has affected human health globally with a significant burden of disease, and also has impeded social and economic development in the areas where it is present. In Africa, many countries have faced serious challenges in controlling malaria, in part due to major limitations in public health systems and primary health care infrastructure. Although China is a developing country, a set of control strategies and measures in different local settings have been implemented successfully by the National Malaria Control Programme over the last 60 years, with a low cost of investment. It is expected that Chinese experience may benefit malaria control in Africa. This review will address the importance and possibility of China-Africa collaboration in control of malaria in targeted African countries, as well as how to proceed toward the goal of elimination where this is technically feasible. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
25. New Progress for Human Rights in Africa.
- Author
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XIA JISHENG
- Subjects
SOCIAL conditions in Africa ,HUMAN rights ,WOMEN in politics ,SOCIAL change ,RWANDAN Genocide, 1994 ,AFRICAN history, 1960- - Abstract
The article discusses human rights, African political reforms and social change. The author reflects on the promotion and protection of human rights in South Africa through a commission. The genocide in Rwanda and the humanitarian crisis in the Darfur region of Sudan are also considered. Other topics include women's political participation and human rights institutions such as the African Human Rights Court.
- Published
- 2008
- Full Text
- View/download PDF
26. Significant overestimation of global aerosol optical thickness by MODIS over land.
- Author
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Xia Xiang'ao
- Subjects
- *
OPTICAL reflection , *SPECTRORADIOMETER , *ROBOTICS - Abstract
Global aerosol optical thickness (AOT) data over land obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) are evaluated through comparisons with AOT data retrieved by Aerosol Robotic Network (AERONET). In general, MODIS overestimates AOT except at a few AERONET sites in Africa and eastern Asia. MODIS/AOTs are, on average, larger than AERONET/AOTs by 0.041 and 0.090 at 470 nm and 660 nm, respectively. The AOT bias at 660 nm is significantly correlated to the surface reflectance at 2130 nm. Both facts suggest that the underestimation of the surface reflectance is the principal reason for this bias at 660 nm. To use the MODIS/AOT at 470 nm is strongly recommended because it is much more reliable than the AOT at 660 nm. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
27. Dynamic HIV/AIDS Parameter Estimation With. Application to a Vaccine Readiness Study in Southern Africa.
- Author
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Filter, R. A., Xia, X., and Gray, C. M.
- Subjects
- *
HIV-positive persons , *VACCINES , *PARAMETER estimation , *MATHEMATICAL optimization , *LEAST squares , *AIDS - Abstract
This paper proposes a procedure of parameter estimation for all parameters of the three-dimensional HIV model. The least square based procedure uses standard optimization routines to allow parameter extraction for individual patients. It is shown how additional information from outside a measurement dataset can be included in the estimation routine to increase the reliability And accuracy of parameter estimates. A dataset from 44 patients of Southern Africa is analyzed to find the set point and the time until set point for these patients together with an estimate of the model parameters with confidence intervals for the cohort The procedure is also applied to a long-term dataset of the HIV/AIDS progression to find possible variations in parameters. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
28. Rapid and nondestructive determination of sesamin and sesamolin in Chinese sesames by near-infrared spectroscopy coupling with chemometric method.
- Author
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Xia, Zhenzhen, Yi, Tian, and Liu, Yan
- Subjects
- *
SESAME , *STANDARD deviations , *SPECTROMETRY , *INFRARED spectra - Abstract
Sesame was one of the most important crops in Africa and east Asia. The sesamin and sesamolin in sesames have shown various pharmacological, biological and physiologic activities. In this study, a rapid and nondestructive method for determination of sesamin and sesamolin in Chinese sesames by near-infrared spectroscopy coupled with chemometric method was proposed. The near infrared spectra of sesame samples from three different Chinese areas were collected and the partial least squares (PLS) was used to construct the quantitative models. The spectral preprocessing and variable selection methods were adopted to improve the predictability and stability of the model. Reasonable quantitative results can be obtained when the samples used for model construction and prediction were harvested in same years. For sesamin and sesamolin, the correlation coefficient (R) and root mean square error prediction (RMSEP) were 0.9754, 0.9636 and 151.2951, 39.7720, respectively. The optimized models seem less effective when they were used to predict the samples harvested in other years or countries. However, acceptable results can still be obtained. Unlabelled Image • Sesamin and sesamolin in sesame from three Chinese provinces were calculated by NIR and PLS. • Spectral pretreatment and variable selection method were adopted to optimize the model. • Prediction results of sesamin and sesamolin by optimized model and HPLC method were close. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
29. Genetically Modified Rabies Virus Vector-Based Rift Valley Fever Virus Vaccine is Safe and Induces Efficacious Immune Responses in Mice.
- Author
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Zhang, Shengnan, Hao, Meng, Feng, Na, Jin, Hongli, Yan, Feihu, Chi, Hang, Wang, Hualei, Han, Qiuxue, Wang, Jianzhong, Wong, Gary, Liu, Bo, Wu, Jun, Bi, Yuhai, Wang, Tiecheng, Sun, Weiyang, Gao, Yuwei, Yang, Songtao, Zhao, Yongkun, and Xia, Xianzhu
- Subjects
RIFT Valley fever ,VIRAL vaccines ,RABIES virus ,IMMUNE response ,HUMORAL immunity ,T cells ,MICE ,CLONORCHIS sinensis - Abstract
Rift Valley fever virus (RVFV), which causes Rift Valley fever (RVF), is a mosquito-borne zoonotic pathogen that causes serious morbidity and mortality in livestock and humans. RVF is a World Health Organization (WHO) priority disease and, together with rabies, is a major health burden in Africa. Here, we present the development and characterization of an inactivated recombinant RVFV and rabies virus (RABV) vaccine candidate (rSRV9-eGn). Immunization with rSRV9-eGn stimulated the production of RVFV-specific IgG antibodies and induced humoral and cellular immunity in mice but did not induce the production of neutralizing antibodies. IgG1 and IgG2a were the main isotypes observed by IgG subtype detection, and IgG3 antibodies were not detected. The ratios of IgG1/IgG2a > 1 indicated a Type 2 humoral immune response. An effective vaccine is intended to establish a long-lived population of memory T cells, and mice generated memory cells among the proliferating T cell population after immunization with rSRV9-eGn, with effector memory T cells (T
EM ) as the major population. Due to the lack of prophylactic treatment experiments, it is impossible to predict whether this vaccine can protect animals from RVFV infection with only high titres of anti-RVFV IgG antibodies and no neutralizing antibodies induced, and thus, protection confirmation needs further verification. However, this RVFV vaccine designed with RABV as the vector provides ideas for the development of vaccines that prevent RVFV and RABV infections. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
30. WAGING WAR ON POVERTY.
- Author
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Yuanyuan, Xia
- Subjects
- *
AFRICA-China relations , *COOPERATIVE agriculture , *POVERTY , *AGRICULTURAL productivity - Abstract
The article presents views of former Ugandan Minister of Agriculture shared Victoria Sekitoleko on the focus of China and Africa on managing increasing poverty in both countries. Various topics she discussed include training given to Africans on agricultural production, and agricultural cooperation between China and Africa.
- Published
- 2018
31. Linking Arms.
- Author
-
Yuanyuan, Xia
- Subjects
- *
SCHOLARS , *GROSS domestic product - Abstract
The article focuses on the Chinese and African scholars discussion at the Seventh Meeting of China-Africa Think Tanks Forum Beijing, China on July 4, 2018. Topics discussed including views of Justin Yifu Lin,Dean of the Institute of New Structural Economics on the Gross domestic product (GDP) of China and Africa, views of Li Yafang, President of Beijing Review on Chinese and African media; and views of Chen Xiaodong, Assistant Minister of Foreign on the factor for debt problems in Africa.
- Published
- 2018
32. The Plasmodium vivax in China: decreased in local cases but increased imported cases from Southeast Asia and Africa.
- Author
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Feng, Jun, Xiao, Huihui, Zhang, Li, Yan, He, Feng, Xinyu, Fang, Wen, and Xia, Zhigui
- Subjects
PLASMODIUM vivax ,MIGRANT labor ,PLASMODIUM - Abstract
Currently the local P. vivax was sharply decreased while the imported vivax malaria increased in China. Despite Southeast Asia was still the main import source of vivax malaria, the trend of Africa become serious, especially for west and central Africa. Herein we have clarified the trend of P. vivax in China from 2004-2012, and made some analysis for the differences of imported vivax back from different regions. There are significantly different of P. vivax between Southeast Asia and Africa, also the difference was observed for different regions in Africa. Additionally, we have explored the possibility for the difference of the P. vivax between migrant workers back from west and central Africa and the prevalence of local population. This reminds us that surveillance and training should be strengthened by medical staffs on the imported P. vivax cases reported especially from west and central Africa, in order to reduce the risk of malaria reintroduction and, specific tools should be developed, as well as the epidemiological study to avoid the misdiagnosis such as P. ovale and P. vivax. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
33. Cytogenetic map for Anopheles nili: Application for population genetics and comparative physical mapping
- Author
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Sharakhova, Maria V., Antonio-Nkondjio, Christophe, Xia, Ai, Ndo, Cyrille, Awono-Ambene, Parfait, Simard, Frederic, and Sharakhov, Igor V.
- Subjects
- *
ANOPHELES , *CYTOGENETICS , *MOSQUITO vectors , *MALARIA , *GIANT chromosomes , *GENETIC carriers , *GENETIC polymorphisms , *GENETIC markers - Abstract
Abstract: Anopheles nili is one of the major malaria vectors in Africa with a wide geographic distribution. However, the taxonomic and population genetic studies on this species are scarce. New research tools are urgently needed to genetically characterize this important malaria vector. In this study, a high-resolution cytogenetic map was developed for An. nili polytene chromosomes. Chromosomes were straightened and subdivided into 46 numbered divisions according to the banding pattern. Population analysis of An. nili females collected in Burkina Faso revealed the presence of two highly polymorphic inversions on the 2R chromosomal arm. A statistically significant departure from Hardy–Weinberg equilibrium due to a deficit in heterozygotes was detected for inversion 2Rb. To determine chromosome homologies and gene order conservation between An. nili and other major malaria vectors, PCR probes based on the An. gambiae coding sequences were mapped to An. nili chromosomes. Comparative mapping demonstrated that An. nili chromosomes have an An. stephensi-like arm association and that whole-arm translocations and paracentric inversions were the major types of rearrangement in evolution of these mosquitoes. The minimum number of fixed inversions among An. nili, An. gambiae, and An. stephensi was calculated using the Multiple Genome Rearrangements (MGR), Genome Rearrangements In Man and Mouse (GRIMM), and Sorting Permutation by Reversals and block-INterchanGes (SPRING) programs. The data suggest that the An. nili is, at least, as diverged from An. gambiae as An. stephensi. We provide evidence that 2La/a arrangement of An. gambiae is present in outgroup species An. nili and An. stephensi confirming the ancestral status of the 2La inversion in the An. gambiae complex. Availability of the new polytene chromosome map, polymorphic inversions, and physically mapped DNA markers for An. nili will further stimulate population genetic, taxonomic, and genomic studies of this neglected malaria vector. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
34. Maternal exposure to fine particulate matter and preterm birth and low birth weight in Africa.
- Author
-
Bachwenkizi, Jovine, Liu, Cong, Meng, Xia, Zhang, Lina, Wang, Weidong, van Donkelaar, Aaron, Martin, Randall V., Hammer, Melanie S., Chen, Renjie, and Kan, Haidong
- Subjects
- *
LOW birth weight , *PREMATURE labor , *PARTICULATE matter , *MATERNAL exposure , *BIRTH weight - Abstract
[Display omitted] • Evidence is scarce on PM 2.5 exposure and birth outcome in African countries. • Use of Satellite-derived PM 2.5 estimates and the Demographic Health and Surveys data. • PM 2.5 exposure was significantly associated with preterm birth (8%) and low birth weight (28%) • Associations were modified by region, and maternal, infant, household characteristics. Fine particulate matter (PM 2.5) exposure has been reported to adversely affect birth outcomes, but the evidence is limited, particularly in low- and middle-income countries (LMICs). We assessed the associations between maternal PM 2.5 exposure and low birth weight (LBW) and preterm birth (PTB) in Africa. We used standard Demographic and Health Surveys (DHS) data (2005–2015) from 15 countries in Africa to conduct a cross-sectional study. The study population was composed of 131,594 births with detailed information on maternal and household variables. LBW was defined as a birth weight of < 2500 g after 37 weeks, and PTB was defined as live birth occurring before 37 weeks of gestation. Average exposure to PM 2.5 during pregnancy was estimated using satellite-based models. Multivariable logistic regression models were constructed, and analyses of data by region (Western, Eastern, Central, and Southern Africa) and data stratified by potential effect modifiers were conducted. A total of 13,214 (10%) LBW and 4,377 (3.3%) PTB cases were identified. An interquartile range (IQR) (33.9 μg/m3) increase in PM 2.5 during pregnancy was associated with increased odds of LBW and PTB, with odds ratios (ORs) of 1.28 (95% CI: 1.23, 1.34) and 1.08 (95% CI: 1.01, 1.16), respectively. Region-specific analyses revealed significant associations between PM 2.5 and LBW in all regions, and significant associations between PM 2.5 and PTB in Western and Southern Africa. Subgroup analyses revealed that the association between PM 2.5 and LBW was present in all subgroups, and stronger associations were observed in female infants, while the association between PM 2.5 and PTB was larger in subgroups of older individuals living in urban areas. This multicountry study in Africa demonstrated significant associations between maternal exposure to PM 2.5 and higher odds of LBW and PTB. Our findings may facilitate air quality control strategies that address adverse birth outcomes in LMICs. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
35. Fine particulate matter constituents and infant mortality in Africa: A multicountry study.
- Author
-
Bachwenkizi, Jovine, Liu, Cong, Meng, Xia, Zhang, Lina, Wang, Weidong, van Donkelaar, Aaron, Martin, Randall V., Hammer, Melanie S., Chen, Renjie, and Kan, Haidong
- Subjects
- *
INFANT mortality , *PARTICULATE matter , *SOOT , *DEMOGRAPHIC surveys , *LOGISTIC regression analysis , *BIOMASS burning , *BIRTH certificates - Abstract
• Limited evidence on the PM 2.5 constituents - infant mortality association in developing countries. • A multi-country cross-sectional study based on the Demographic and Health Surveys in Africa. • PM 2.5 was associated with increased infant mortality across 15 countries in Africa. • PM 2.5 carbonaceous fractions and sulfate play a major important role in infant mortality. Few studies have investigated the association between exposure to fine particulate matter (PM 2.5) and infant mortality in developing countries, especially for the health effects of specific PM 2.5 constituents. We aimed to examine the association of long-term exposure to specific PM 2.5 constituents with infant mortality in 15 African countries from 2005 to 2015. Based on the Demographic and Health Surveys (DHS) dataset, we included birth history records from 15 countries in Africa and conducted a multicountry cross-sectional study to examine the associations between specific PM 2.5 constituents and infant mortality. We estimated annual residential exposure using satellite-derived PM 2.5 for mass and a chemical transport model (GEOS-Chem) for its six constituents, including organic matter (OM), black carbon (BC), sulfate (SO 4 2−), nitrate (NO 3 −), ammonium (NH 4 +), and soil dust (DUST). Multivariable logistic regression analysis was employed by fitting single-constituent models, the constituent-PM 2.5 models, and the constituent-residual models. We also conducted stratified analyses by potential effect modifiers and examined the specific associations for each country. We found positive and significant associations between PM 2.5 total mass and most of its constituents with infant mortality. In the single-constituent model, for an IQR increase in pollutant concentrations, the odds ratio (OR) of infant mortality was 1.03 (95 %CI; 1.01, 1.06) for PM 2.5 total mass, and was 1.04 (95 %CI: 1.02, 1.06), 1.04 (95 %CI: 1.02, 1.05), 1.02 (95 %CI: 1.00, 1.03), 1.04 (1.01, 1.06) for BC, OM, SO 4 2−, and DUST, respectively. The associations of BC, OM, and SO 4 2− remained significant in the other two models. We observed larger estimates in subgroups with older maternal age, living in urban areas, using unclean cooking energy, and with access to piped water. The associations varied among countries, and by different constituents. The carbonaceous fractions and sulfate play a major important role among PM 2.5 constituents on infant mortality. Our findings have certain policy implications for implementing effective measures for targeted reduction in specific sources (fossil fuel combustion and biomass burning) of PM 2.5 constituents against the risk of infant mortality. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
36. Magnus representation of genome sequences.
- Author
-
Wu, Chengyuan, Ren, Shiquan, Wu, Jie, and Xia, Kelin
- Subjects
- *
NUCLEOTIDE sequencing , *BACTERIAL genomes , *EBOLA virus , *FILOVIRIDAE , *SEQUENCE alignment - Abstract
• We introduce an alignment-free method, the Magnus Representation, to analyze genome sequences. • The Magnus Representation captures higher-order information in genome sequences. • We combine our approach with the idea of k-mers to define an effectively computable Mean Magnus Vector. • We perform phylogenetic analysis on three datasets: mosquito-borne viruses, filoviruses, and bacterial genomes. We introduce an alignment-free method, the Magnus Representation, to analyze genome sequences. The Magnus Representation captures higher-order information in genome sequences. We combine our approach with the idea of k -mers to define an effectively computable Mean Magnus Vector. We perform phylogenetic analysis on three datasets: mosquito-borne viruses, filoviruses, and bacterial genomes. Our results on ebolaviruses are consistent with previous phylogenetic analyses, and confirm the modern viewpoint that the 2014 West African Ebola outbreak likely originated from Central Africa. Our analysis also confirms the close relationship between Bundibugyo ebolavirus and Taï Forest ebolavirus. For bacterial genomes, our method is able to classify relatively well at the family and genus level, as well as at higher levels such as phylum level. The bacterial genomes are also separated well into Gram-positive and Gram-negative subgroups. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
37. Tiratricol inhibits yellow fever virus replication through targeting viral RNA-dependent RNA polymerase of NS5.
- Author
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Ren, Hao, Wang, Jiaqi, Tang, Hailin, Qian, Xijing, Xia, Binghui, Luo, Zhenghan, Xu, Zhenghao, Qi, Zhongtian, and Zhao, Ping
- Subjects
- *
RNA replicase , *YELLOW fever , *VIRAL nonstructural proteins , *PHYTOPLASMAS , *VIRAL replication , *SURFACE plasmon resonance , *CUCUMBER mosaic virus - Abstract
Yellow fever virus (YFV) infection is a major public concern that threatens a large population in South America and Africa. No specific antiviral drugs are available for treating yellow fever. Here, we report that tiratricol (triiodothyroacetic acid, TRIAC), a clinically approved drug used to treat thyroid hormone resistance syndrome (THRS), is a potent YFV inhibitor both in host cells and in animal models.An in vitro study demonstrates that TRIAC remarkably suppresses viral RNA synthesis and protein expression in a dose-dependent manner in human hepatoma cell lines (Huh-7) with an EC50 value of 2.07 μM and a CC50 value of 385.77 μM respectively. The surface plasmon resonance assay and molecular docking analysis indicate that TRIAC hinders viral replication by binding to the RNA-dependent RNA polymerase (RdRp) domain of viral nonstructural protein NS5, probably through interacting with the active sites of RdRp.The inhibitory effect of TRIAC in vivo is also confirmed in 3-week old C57BL/6 mice challenged with YFV infection, from which the survival of the mice as well as lesions and infection in their tissues and serum issignificantly promoted following oral administration of TRIAC (0.2 mg/kg/day). Additionally, TRIAC shows a broad-spectrum antiviral activity against multiple flaviviruses such as TBEV, WNV,ZIKV, andJEV in vitro. Our data demonstrate that the TH analogue TRIAC is an effective anti-YFV compound and may act as a potential therapeutic candidate for the treatment of YFV infection if its clinical importance is determined in patients in future. • Tiratricol is a potent YFV inhibitor both in host cells and animal models. • TRIAC hinders YFV replication by binding to the RdRp domain of viral NS5 protein. • TRIAC shows a broad-spectrum antiviral activity against multiple flaviviruses such as TBEV, WNV, ZIKV, or JEV in vitro. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
38. Phylogeny, character evolution, and biogeography of the fern genus Bolbitis (Dryopteridaceae).
- Author
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Nie, Li-Yun, Zhang, Liang, Liang, Zhen-Long, Pollawatn, Rossarin, Yan, Yue-Hong, Thi Lu, Ngan, Knapp, Ralf, Wan, Xia, Cicuzza, Daniele, Cheng, Xin-Xin, Chen, Hong-Feng, Wang, Ai-Hua, Liao, Yu-Jie, Wang, Fa-Guo, and Zhang, Li-Bing
- Subjects
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PHYLOGENY , *MOLECULAR phylogeny , *FERNS , *BIOGEOGRAPHY , *DNA sequencing - Abstract
[Display omitted] • 169 accessions representing ca. 68 (85% of total) species of Bolbitis are sampled. • Species of Bolbitis are resolved into four major clades. • Six well-supported subclades are identified in the most speciose Asian clade. • Evolution of six characters is analyzed and free venation evolved from anastomosing venation in Bolbitis. • Bolbitis originated from Africa and a dispersal from Asia resulted in continental disjunction between Africa and America. Bolbitis is a pantropical fern genus of Dryopteridaceae with ca. 80 species mainly in tropical Asia. Earlier studies confirmed the monophyly of Bolbitis when Mickelia is excluded and identified three major clades in Bolbitis. However, earlier studies are based on relatively small sampling and the majority of Asian species are not sampled. In this study, DNA sequences of three plastid markers of 169 accessions representing ca. 68 (85 % of total) species of Bolbitis in nine out of the 10 series recognized by Hennipman (1977), and 54 accessions representing the five remaining bolbitidoid genera are used to infer a global phylogeny with a focus on Asian species. The major results include: (1) Bolbitis is strongly supported as monophyletic; (2) species of Bolbitis are resolved into four major clades and their relationships are: the Malagasy/Mascarene clade is sister to the rest, followed by the African clade which is sister to the American clade + the Asian clade; (3) six well-supported subclades are identified in the most speciose Asian clade; (4) the free-veined Egenolfia is embedded in Bolbitis and is paraphyletic in relation to species with anastomosing venation; (5) three series sensu Hennipman (1977), B. ser. Alienae , B. ser. Egenolfianae , and B. ser. Heteroclitae , are paraphyletic or polyphyletic; (6) evolution of six morphological characters is analyzed and free venation is found to have evolved from anastomosing venation and reversed to free venation in Bolbitis ; and (7) biogeographical implications are drawn and it is shown that a single recent dispersal from Asia resulted in continental disjunction of closely related ferns of Bolbitis between Africa and America. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
39. Minimum carbon uptake controls the interannual variability of ecosystem productivity in tropical evergreen forests.
- Author
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Li, Zhao, Ahlström, Anders, Tian, Feng, Gärtner, Antje, Jiang, Ming, and Xia, Jianyang
- Subjects
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TROPICAL forests , *FOREST productivity , *CARBON , *CLIMATE change , *ECOSYSTEMS - Abstract
Tropical evergreen forests contribute an important part to the interannual variability (IAV) of the global terrestrial gross primary productivity (GPP). Due to its year-round growing-season, high minimum carbon uptake (GPP min) and dry season greening-up, the key processes driving the GPP variability across seasonal to interannual scale are still in debate. Here, we analyzed the time-series of FLUXCOM GPP (1980–2013), sun-induced fluorescence (SIF; 2001–2013) and site-level GPP measurements in three tropical evergreen forests regions (i.e., Amazon, Africa, and Southeast Asia). We decomposed the annual accumulated GPP into the basic and recurrent GPP, which represent the accumulated minimum and seasonal vegetation productivity, respectively. Then we quantified the proportion of each component and estimated the contribution to the IAV of GPP. We find that the basic GPP overwhelmed the recurrent GPP with the averaging ratio of 4.2:1 across the global tropical regions, and dominated the IAV of annual total GPP in 83.7% of the tropical evergreen forest areas. The high contribution of the basic GPP resulted from the great sensitivity of GPP min to rainfall changes among years. The decomposition of the basic and recurrent GPP sheds new light on the understanding of tropical GPP variability in responding to climate change at seasonal and annual scale. Our study highlights the critical role of the GPP min in shaping temporal dynamics of the annual GPP in tropical forests and emphasizes the importance of managing tropical forest of the shifting periods between wet-dry seasons in global tropical regions. • Visualizing the seasonal recurrence of tropical forests. • Revealing the role of the minimum carbon uptake in shaping the inter-annual variability of GPP. • Bridging the understandings of GPP variations at seasonal and inter-annual scales. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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