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Pro/E Wild Fire中零件库的建立方法 被引量:5
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作者 石晶 焦洪宇 张涛 《机械设计与制造》 北大核心 2005年第5期137-138,共2页
以Pro/E Wild Fire软件为基础,详细地论述了零件库的建立方法,分析了每种方法的优缺点,提出了适用范围,使零件库的建立更加简单化,从而有效的提高了实体建模速度,缩短了设计周期。
关键词 PRO/ENGINEER wild fire 族表 自定义特征 编程
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Lightning in a Forest (Wild) Fire: Mechanism at the Molecular Level
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作者 See Leang Chin Xueliang Guo +4 位作者 Harmut Schroeder Huanbin Xu Tie-Jun Wang Ruxin Li Weiwei Liu 《Atmospheric and Climate Sciences》 2024年第1期128-135,共8页
The mechanism of lightning that ignites a forest fire and the lightning that occurs above a forest fire are explained at the molecular level. It is based on two phenomena, namely, internal charge separation inside the... The mechanism of lightning that ignites a forest fire and the lightning that occurs above a forest fire are explained at the molecular level. It is based on two phenomena, namely, internal charge separation inside the atmospheric cloud particles and the existence of a layer of positively charged hydrogen atoms sticking out of the surface of the liquid layer of water on the surface of rimers. Strong turbulence-driven collisions of the ice particles and water droplets with the rimers give rise to breakups of the ice particles and water droplets into positively and negatively charged fragments leading to charge separation. Hot weather in a forest contributes to the updraft of hot and humid air, which follows the same physical/chemical processes of normal lightning proposed and explained recently[1]. Lightning would have a high probability of lighting up and burning the dry biological materials in the ground of the forest, leading to a forest (wild) fire. The burning of trees and other plants would release a lot of heat and moisture together with a lot of smoke particles (aerosols) becoming a strong updraft. The condition for creating lightning is again satisfied which would result in further lightning high above the forest wild fire. 展开更多
关键词 Forest wild fire LIGHTNING Molecular Level
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Clinicopathological alterations in wild mammals from the reservoir system of Trypanosoma cruzi:a scoping review
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作者 Ricardo Sanchez Pérez JoséManuel Aranda-Coello +1 位作者 JoséAntonio De Fuentes Vicente Oscar Rico Chavez 《Animal Diseases》 CAS 2024年第1期48-58,共11页
Trypanosoma cruzi is the etiologic agent of Chagas disease.This flagellated protozoan is transmitted to humans as well as different species of domestic and wild animals via vectors from the Reduviidae family(known as&... Trypanosoma cruzi is the etiologic agent of Chagas disease.This flagellated protozoan is transmitted to humans as well as different species of domestic and wild animals via vectors from the Reduviidae family(known as"kissing bugs").Despite the fact that hundreds of species of wild mammals are part of the reservoir system,the morphologi-cal changes and clinical manifestations resulting from the pathogenesis of the infection have been largely neglected.The aim of this review is to systematically compile the available information regarding clinicopathological altera-tions in wild mammals due to natural infection by T.cruzi.Information was obtained from six online bibliographic data search platforms,resulting in the identification of 29 publications that met the inclusion criteria.Mortality was the most common clinical manifestation,cardiac damage was the main finding at necropsy,and lymphoplas-macytic inflammation was the most frequent microscopic injury.Thus,regardless of its role as a reservoir,T.cruzi has the potential to affect the health status of wild mammals,a situation that highlights the need for further research to analyze,measure,and compare its effects at both the individual and population levels. 展开更多
关键词 Trypanosoma cruzi Chagas disease American trypanosomiasis Clinicopathological alterations Natural infection wild mammals
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Comparative Study of Genetic Structure and Genetic Diversity betweenWild and Cultivated Populations of Taxus cuspidata,Northeast China
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作者 Dandan Wang Xiaohong Li Yanwen Zhang 《Phyton-International Journal of Experimental Botany》 SCIE 2024年第2期355-369,共15页
Taxus cuspidata is a rare plant with important medicinal and ornamental value.Aiming at the obvious differences between wild and cultivated populations of T.cuspidata from Northeast China,a total of 61 samples,that is... Taxus cuspidata is a rare plant with important medicinal and ornamental value.Aiming at the obvious differences between wild and cultivated populations of T.cuspidata from Northeast China,a total of 61 samples,that is,33 wild yews and 28 cultivated yews were used to analyze the differences and correlations of the kinship,genetic diversity,and genetic structure between them by specific length amplified fragment sequencing(SLAF-seq).Finally,470725 polymorphic SLAF tags and 58622 valid SNP markers were obtained.Phylogenetic analysis showed that 61 samples were classified into 2 clusters:wild populations and cultivated populations,and some wild yews were categorized into the cultivated populations;the genetic diversity analysis showed that the Nei diversity index of wild populations(0.4068)was smaller than that of cultivated populations(0.4414),and the polymorphic information content(PIC)of wild populations(0.2861)was smaller than that of cultivated populations(0.3309).The genetic differentiation analysis showed that the total populations of gene diversity(H_(t))of cultivated and wild populations were respectively 0.8159 and 0.5685,the coefficient of gene differentiation(G_(st))of cultivated and wild populations was respectively 0.3021 and 0.1068,and the gene flow(N_(m))(2.4967)of wild populations was larger than cultivated populations(0.8199).The molecular variance(AMOVA)revealed that inter-population variation accounted for 29.57%of the total genetic variation,while intra-population variation accounted for 70.42% of the total genetic variation(p<0.001),this suggested that the genetic variation in the T.cuspidata is mainly attributed to within-population factors.In conclusion,the genetic distance between geographical ecological groups of wild populations was generally smaller than that of cultivated populations,and the degree of genetic diversity and genetic differentiation was smaller than that of cultivated populations.As evident,the utilization of SLAF-seq technology enables efficient and accurate development of SNP markers suitable for genetic analysis of T.cuspidata species.These developed SNP markers can provide a molecular foundation for T.cuspidata breeding,construction of genetic maps,variety identification,and association analysis of agronomic traits. 展开更多
关键词 T.cuspidata SLAF-seq SNP wild population cultivated population genetic structure
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The Influence of Chuang Tsu on Oscar Wilde’s Literary Works
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作者 XU Hai-hua 《Sino-US English Teaching》 2024年第3期138-141,共4页
Oscar Wilde,the renowned British writer,was deeply influenced by Eastern culture,particularly by Chuang Tsu’s“Thought of Doing Nothing”,a Taoist concept of human conduct.Wilde not only embraced this philosophy,but ... Oscar Wilde,the renowned British writer,was deeply influenced by Eastern culture,particularly by Chuang Tsu’s“Thought of Doing Nothing”,a Taoist concept of human conduct.Wilde not only embraced this philosophy,but also incorporated it into his literary creations and art criticism,enhancing the steadfastness of his own value judgments. 展开更多
关键词 Oscar wilde Chuang Tsu “Thought of Doing Nothing”
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Retrospective analysis of two northern California wild-land fires via Landsat five satellite imagery and Normalized Difference Vegetation Index (NDVI) 被引量:1
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作者 Bennett Sall Michael W. Jenkins James Pushnik 《Open Journal of Ecology》 2013年第4期311-323,共13页
Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of t... Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of this research was to study two northern California wild-land fires: Butte Humboldt Complex and Butte Lightning Complex of 2008 and assessment of vegetation recovery after the fires via ground based measurements and utilization of Landsat 5 imagery and analysis software to assess landscape change. Multi-temporal and burn severity dynamics and assessment through satellite imagery were used to visually ascertain levels of landscape change, under two temporal scales. Visual interpretation indicated noticeable levels of landscape change and relevant insight into the magnitude and impact of both wild-land fires. Normalized Burn Ratio (NBR) and delta NBR (DNBR) data allowed for quantitative analysis of burn severity levels. DNBR results indicate low severity and low re-growth for Butte Humboldt Complex “burned center” subplots. In contrast, DNBR values for Butte Lightning Complex “burned center” subplots indicated low-moderate burn severity levels. 展开更多
关键词 wild-Land fire BURN Severity Vegetation Recovery Normalized Difference VEGETATIVE Index (NDVI) Normalized BURN Ratio (NBR)
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The challenge of applying governance and sustainable development to wildland fire management in Southern Europe
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作者 Susana Aguilar Cristina Montiel 《Journal of Forestry Research》 SCIE CAS CSCD 2011年第4期627-639,共13页
This paper discusses participatory processes in wildland fire management (WFM). Participation is an essential element of both the European Sustainable Development (SD) Strategy and the White Paper on Governance. G... This paper discusses participatory processes in wildland fire management (WFM). Participation is an essential element of both the European Sustainable Development (SD) Strategy and the White Paper on Governance. Governance end SD have thus become an interconnected challenge to be applied to WFM (as a sub-area in forest policy), amongst other policies. An overspread weakness in WFM is lack of real participation of stakeholders. Absence of (or deficient) participation can seriously impair contribution of this group to WFM in high-risk areas and runs counter governance and the SDS. Further, this weakness might prevent an efficient use of fire as a land management tool (prescribed burning, PB) and as a technique for fighting wildfire (suppression fire, SF). Even though these fire practices have been well known in many different places, they have been increasingly neglected or Prohibited over time in Southern Europe. At present, forest and fire fighting administrations are turning their eyes back on them and analyzing the benefits of using fire in relation to preventive and suppressive actions. Therefore, participatory and diffusion mechanisms (the latter adopting the shape of national and international experts' networks) are required in order to solve the so- called fire paradox: that is, the need to move from a one-dimensinnal perception of the negative impacts of fire to a more sophisticated one that also stresses its positive effects. Governance, based on broad social participation, and diffusion, through fire networks, are of utmost importance in order, first, to diminish long-standing suspicion amongst different interests as to the use of fire and, secondly, to diffuse best practices associated with PB and SF. Most importantly, the ELI should exercise its environmental leadership so that these new fire practices and sustainable WFM are diffused across the international arena. 展开更多
关键词 GOVERNANCE sustainable development forestry policy wild-fire management social participation
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Wildfire Occurrence: Integrated Model for Risk Analysis and Operative Suppression Aspects Management
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作者 Laura Bonora Claudio Claudio Conese +2 位作者 Enrico Marchi Enrico Tesi Niccolò Brachetti Montorselli 《American Journal of Plant Sciences》 2013年第3期705-710,共6页
Generally forest fires are related to human activities and need an effective fire prevention and suppression organization, based on a deep knowledge of the territory, fire behaviour and suppression system resources ne... Generally forest fires are related to human activities and need an effective fire prevention and suppression organization, based on a deep knowledge of the territory, fire behaviour and suppression system resources network. To organise monitoring, prevention and fire fighting operations, the knowledge of the risk level for different areas is important. To evaluate the probability that a forest fire occurs and to organise prevention and management of fire fighting activities, both simple and easy-to-use risk and operational difficulty indices were implemented. CNR-IBIMET and DISTAF Dept., on commitment of Tuscany Region, developed a multistep process for the evaluation of the risk, that can be used to assess land planning and to organise seasonal fire fighting resources. This model is called Final Risk Index (FRI);it is the result of the combination of the following two indices, which are initially developed separately. The concerned indices are the Global Risk Index (GRI), and Operational Difficulty Index in Fire Fighting (ODIF). The fire risk index processes different parameters to generate two hazards: static and dynamic, merged to obtain the Global Risk Index (GRI). It is very helpful to estimate the probability of forest fire occurrence, but it does not provide information on forest fire extinction difficulties. The operational difficulty index in fire fighting (ODIF) resumes all the factors affecting fire fighting activity by air and by ground and suggests the extinction efficiency of forest fires in a given area. Thus FRI improves aspects of the fire prevention planning, focused to the needs of a public operative structure. The objective was modelling the links between the main components in ignition and fire fighting actions to produce an easy to use tool to face the emergences, also foreseeing forest fires regime changes in the coming decades. 展开更多
关键词 wild-Land fire IGNITION RISK Infrastructural RISK METEOROLOGICAL RISK
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Metagenomic Analysis of Environmental Samples from Wildlife Rescue Station at Poyang Lake, China
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作者 LIU Jia LI Xi Yan +4 位作者 SONG Wen Tao ZENG Xiao Xu LI Hui YANG Lei WANG Da Yan 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2023年第7期595-603,共9页
Objective To improve the understanding of the virome and bacterial microbiome in the wildlife rescue station of Poyang Lake,China.Methods Ten smear samples were collected in March 2019.Metagenomic sequencing was perfo... Objective To improve the understanding of the virome and bacterial microbiome in the wildlife rescue station of Poyang Lake,China.Methods Ten smear samples were collected in March 2019.Metagenomic sequencing was performed to delineate bacterial and viral diversity.Taxonomic analysis was performed using the Kraken2 and Bracken methods.A maximum-likelihood tree was constructed based on the RNA-dependent RNA polymerase(RdRp)region of picornavirus.Results We identified 363 bacterial and 6 viral families.A significant difference in microbial and viral abundance was found between samples S01–S09 and S10.In S01–S09,members of Flavobacteriia and Gammaproteobacteria were the most prevalent,while in S10,the most prevalent bacteria class was Actinomycetia.Among S01–S09,members of Myoviridae and Herelleviridae were the most prevalent,while the dominant virus family of S10 was Picornaviridae.The full genome of the pigeon mesivirus-like virus(NC-BM-233)was recovered from S10 and contained an open reading frame of 8,124 nt.It showed the best hit to the pigeon mesivirus 2 polyprotein,with 84.10%amino acid identity.Phylogenetic analysis showed that RdRp clustered into Megrivirus B.Conclusion This study provides an initial assessment of the bacteria and viruses in the cage-smeared samples,broadens our knowledge of viral and bacterial diversity,and is a way to discover potential pathogens in wild birds . 展开更多
关键词 METAGENOMICS Virome Megrivirus B Picornaviridae Poyang Lake wildlife Rescue Station wild Bird
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Novel QTLs from Wild Rice Oryza longistaminata Confer Strong Tolerance to High Temperature at Seedling Stage
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作者 FAN Fengfeng CAI Meng +6 位作者 LUO Xiong LIU Manman YUAN Huanran CHENG Mingxing Ayaz AHMAD LI Nengwu LI Shaoqing 《Rice science》 SCIE CSCD 2023年第6期577-586,共10页
Global warming poses a threat to rice production.Breeding heat-tolerant rice is an effective and economical approach to address this challenge.African rice is a valuable genetic resource for developing heat-tolerant c... Global warming poses a threat to rice production.Breeding heat-tolerant rice is an effective and economical approach to address this challenge.African rice is a valuable genetic resource for developing heat-tolerant crops due to its intricate mechanism for adapting to high temperatures.Oryza longistaminata,a widely distributed wild rice species in Africa,may harbor an even richer gene pool for heat tolerance,which remains untapped.In this study,we identified three heat tolerance QTLs from O.longistaminata at the seedling stage,including novel heat tolerance loci qTT4 and qTT5.Our findings demonstrated that the O.longistaminata alleles for these two QTLs can enhance the heat tolerance of rice seedlings.Remarkably,qTT5 was mapped to a region spanning approximately 287.2 kb,which contains 46 expressing genes.Through the analysis of Gene Ontology and expression differences under heat induction,we identified four candidate genes.Our results lay the foundation for discovering heat tolerance genes underlying O.longistaminata and developing new genetic resources for heat-tolerant rice breeding. 展开更多
关键词 wild rice Oryza longistaminata heat tolerance QTL
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Transcriptome Analysis of a Wild Eggplant Germplasm M239 in Response to Verticillium dahliae Infection
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作者 Liyan Wu Jie Cheng +4 位作者 Yaju Gong Rui Bao Zhibin Li Min Gui Guanghui Du 《Phyton-International Journal of Experimental Botany》 SCIE 2023年第2期591-609,共19页
In this study,wild eggplant germplasm No.M239,which is highly susceptible to Verticillium wilt,was used as the experimental material.The physiological and biochemical indices(SOD,PAL,MDA and soluble protein)of M239 ro... In this study,wild eggplant germplasm No.M239,which is highly susceptible to Verticillium wilt,was used as the experimental material.The physiological and biochemical indices(SOD,PAL,MDA and soluble protein)of M239 roots were measured at different times(0,12,24,36,48,60 and 72 h)post inoculation with Verticillium dahliae,and the key time points for the M239 response to Verticillium wilt infection were screened.Then,RNA-Seq technology was used to screen the differentially expressed genes(DEGs)in M239 roots at 0,12 and 48 h post-inoculation(hpi).The transcriptional results of M239 were also compared with those resistance genes from some reported wild relative Solanum species(S.sisymbriifolium and S.aculeatissimum).Then some DEGs were chosen for validation by qRT–PCR.The results showed that 12 and 48 hpi were the turning points in the changes in all physiological and biochemical indices.A total of 6,783 DEGs were identified by RNA-Seq,including 6,141 DEGs(3,046 upregulated and 3,095 downregulated)at the M_12 h vs.M_0 h,1,903 DEGs(792 upregulated and 1,111 downregulated)at M_48 h vs.M_12 h,and 1,261 DEGs that appeared simultaneously in both stages.KEGG enrichment analysis showed that there were 5 metabolic pathways enriched from DEGs,which were mostly related to primary metabolism,such as glycolysis,amino acid and ribosome biogenesis.Compared with the NCBI non-redundant protein(NR)database,one Ve2 homologous gene and 8 PR protein-related genes were screened.Transcription factor analysis showed that there were a large number of DEGs,such as MYB,AP2-EREBP,bHLH,NAC and Orphans in the two stages.Compared with the reported Verticillium wilt-resistant wild eggplant species,it was found that there were fewer genes and enriched metabolic pathways in the M239 response to Verticillium wilt infection,and it also lacked the response of some known key resistance genes.These results proved that the above resistance genes and metabolic pathways played a key role in the wild eggplant response to V.dahliae infection. 展开更多
关键词 wild eggplant Verticillium wilt transcriptome sequencing differentially expressed gene KEGG pathway
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Growth and Antimony Bioconcentration Characteristics of Wild Ramie(Boehmeria nivea)under Sb Stress in Different Valence States
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作者 Fulong YANG Jiecheng HAN +8 位作者 Yuan WEI Xiaoqi YANG Jinyun PENG Zhi WEI Xiaolian YAN Beiyou ZHANG Qiaoshan LIU Jing ZHOU Guiyuan MENG 《Asian Agricultural Research》 2023年第6期41-45,共5页
[Objectives] To explore the effects of antimony(Sb) in different valence states on the growth and Sb bioconcentration and transfer of wild ramie(Boehmeria nivea). [Methods] A pot experiment was conducted to study the ... [Objectives] To explore the effects of antimony(Sb) in different valence states on the growth and Sb bioconcentration and transfer of wild ramie(Boehmeria nivea). [Methods] A pot experiment was conducted to study the effects of Sb(Ⅲ) and Sb(Ⅴ) stress on plant height, biomass, leaf SPAD value, Sb contents in various organs, Sb bioconcentration and transfer factors, and other indexes. [Results] Both kinds of Sb treatments showed a trend of "first increasing and then decreasing" in plant height as Sb concentration increased. The plant heights in Sb(Ⅲ) treatments with a concentration lower than 1 000 mg/kg and Sb(Ⅴ) treatments with concentrations lower than 4 000 mg/kg were significantly higher than that of the control check(CK);and the Sb(Ⅲ) treatment of the high concentration(4 000 mg/kg) resulted in a significant decrease in plant height, while the 8 000 mg/kg Sb(Ⅴ) treatment still showed an increase in plant height, indicating that the toxicity of Sb(Ⅴ) to wild ramie was significantly lower than that of Sb(Ⅲ). The Sb(Ⅲ) treatments with a concentration lower than 2 000 mg/kg had little effect on the dry weight of the aboveground part, while the treatment with a higher concentration showed a significant decrease;and the dry weights in various concentrations of Sb(Ⅴ) treatments showed no significant differences, but they were significantly higher than the CK and corresponding concentration of Sb(Ⅲ) treatment. Both types of Sb stress could promote the increase of SPAD value in wild ramie leaves, and the performance was significantly higher than the CK. As the concentration of Sb treatment increased, the Sb content in both the aboveground and underground parts showed a significant increase;and the comparison of Sb content under corresponding concentrations of the two types of Sb treatments showed that in the aboveground part, Sb(Ⅲ) was higher than Sb(Ⅴ), while in the underground part, the opposite was true. The bioconcentration factor(BF) of Sb decreased with the increase of Sb treatment concentration overall, and the value of Sb(Ⅴ) was smaller than that of Sb(Ⅲ), but both kinds of Sb stress were significantly smaller than the CK. The transfer factor(TF) of Sb in wild ramie showed a trend of "increasing first and then decreasing" with the concentration of Sb treatment, and various treatments of Sb(Ⅲ) were higher than the CK, with significant differences, while among various treatments of Sb(Ⅴ), except treatment B3, the reduction of which was not significant, other Sb(Ⅴ) treatments showed significant decreases. Comparing the two types of Sb treatments, the BF and TF values of Sb in wild ramie under Sb(Ⅲ) treatments were higher than those under Sb(Ⅴ) treatments, and the TF reached a significant level, indicating that the Sb transport ability of wild ramie under Sb(Ⅲ) treatments was stronger. [Conclusions] This study provides a theoretical basis for the mining of wild ramie Sb restoration genes and the application of large-scale cultivation in ecological restoration. 展开更多
关键词 ANTIMONY wild ramie GROWTH Antimony bioconcentration
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Lack of Evidence for Local Adaptation of the Endangered Karner Blue Butterfly to Its Sole Larval Hostplant—The Wild Lupine
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作者 Kevin Handel Maria Gabriela Bidart 《Advances in Entomology》 2023年第3期172-187,共16页
Local adaptation is an important process that drives the evolution of populations within species, and it can be generally expressed by the higher fitness of individuals raised in their native habitats versus in a fore... Local adaptation is an important process that drives the evolution of populations within species, and it can be generally expressed by the higher fitness of individuals raised in their native habitats versus in a foreign location. The influence of local adaptation is especially prominent in species that subsist in small and/or highly isolated populations. This study evaluated whether the federally endangered Karner blue butterfly, Lycaeides melissa samuelis (Lepidoptera: Lycaenidae) is locally adapted to its exclusive larval host plant, the wild lupine (Lupinus perennis). To test for local adaptation, individuals from a laboratory-raised colony were reared on wild lupine plants from populations belonging to either their native (Indiana) or a foreign (Michigan and Wisconsin) region. For this purpose, lupine plants from the different populations were grown in a common garden in growth chambers, and one Karner blue larva was placed on each plant. Fitness traits related to growth and development were recorded for each butterfly across populations. Days from hatching to pupation and eclosion showed gender-specific significant differences across wild lupine populations and plant genotypes (within populations). The percent survival of butterflies (from hatching to eclosion) also differed among plants from different populations. These results indicate that wild lupine sources can affect some developmental traits of Karner blue butterflies. However, growth-related traits, such as pupal and adult weight of individuals reared in plants from native populations did not differ from those of foreign regions. The apparent absence of local adaptation to wild lupine suggests that, at least, some individuals of this species could be translocated from native populations to foreign reintroduction sites without experiencing decreased fitness levels. However, future studies including more populations across the geographical range of this butterfly are recommended to evaluate other environmental factors that could influence adaptation on a wider spatial scale. 展开更多
关键词 Local Adaptation Karner Blue Butterfly wild Lupine Butterfly Fitness-Related Responses Plant Genotypic Effects
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Analysis and Evaluation of Nutrient Composition in the Wild, Pond- and Lake-Cultured Topmouth Culter (Culter alburnus)
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作者 Zhigang He Hao Wu +5 位作者 Jinglong Li Xiaofei Cheng Xing Tian Shiming Deng Xunhua Liu Dongwu Wang 《Agricultural Sciences》 2023年第12期1675-1687,共13页
Research was conducted on topmouth culter (Culter alburnus) grown in ponds and lakes as well as wild types in order to determine their chemical composition and nutritional value. There are three types of fish that dif... Research was conducted on topmouth culter (Culter alburnus) grown in ponds and lakes as well as wild types in order to determine their chemical composition and nutritional value. There are three types of fish that differ in their proximate composition, amino acids, fatty acids, and minerals. Wild fish had a significantly lower crude lipid contents than cultured fish (P P ∑PUFAs) showed an obviously opposite trend. As compared with cultured fish, wild fish had significantly higher levels of n-3 PUFAs, arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahxaenoic acid (DHA) (P P > 0.05), except for Na, Fe and Se. In conclusion, diet composition and external aqueous environment may determine the differences between wild and cultured topmouth culter. 展开更多
关键词 Topmouth Culter (Culter alburnus) Cultured and wild Fish Amino Acids Fatty Acids Mineral Composition
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Diversity and Distribution of Wild Musa in Nagaland, India
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作者 Chitta Ranjan Deb Punatemjen Tiatemsu +1 位作者 Thejavitsu Noah Vupru Asosii Paul 《Open Journal of Forestry》 2023年第3期315-337,共23页
The state of Nagaland is located in a region known to be a micro-centre of Musa evolution. The prevailing agro-climatic conditions are known to support various members of the genus. This study documents 12 species, wh... The state of Nagaland is located in a region known to be a micro-centre of Musa evolution. The prevailing agro-climatic conditions are known to support various members of the genus. This study documents 12 species, which is an ideal representation of the rich diversity of this genus in an area of 16,579 sq. km. The various species were classified using morphological descriptors based on INIBAP, 1996 following the subsequent collection of the live specimen. The various species documented have been found to exist in single populations or in association with other species and their distribution depends on the varying altitudinal profile as well as the agro-climatic and topographical condition of the environment. 展开更多
关键词 DESCRIPTORS wild Musa Diversity Musa Distribution Nagaland
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基于改进Ratio统计量的重尾AR(p)时间序列均值变点检验
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作者 张思 刘叶 金浩 《统计与决策》 北大核心 2024年第2期52-57,共6页
文章提出两个改进的Ratio统计量来研究重尾AR(p)时间序列均值变点检验问题,在原假设下推导了统计量的渐近分布,且在备择假设下证明了其一致性。由于重尾指数未知且难以估计,因此结合Wild Bootstrap重抽样方法来确定渐近分布的临界值;在... 文章提出两个改进的Ratio统计量来研究重尾AR(p)时间序列均值变点检验问题,在原假设下推导了统计量的渐近分布,且在备择假设下证明了其一致性。由于重尾指数未知且难以估计,因此结合Wild Bootstrap重抽样方法来确定渐近分布的临界值;在均值变点存在的情形下,给出了变点位置的一致估计量。数值模拟结果表明:统计量的临界值均不受重尾指数和自回归系数的影响,其经验水平和经验势均取得满意的效果;尤其在原假设下,积分型Ratio统计量的经验水平表现出更好的稳健性,而在备择假设下,最值型Ratio统计量则具备更好的显著性。最后,基于一组股票数据,从实际应用角度进一步阐明所提方法的有效性和可行性。 展开更多
关键词 重尾序列 Ratio统计量 均值变点 wild Bootstrap
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我国证券市场有效性的Wild Bootstrap方差比检验 被引量:17
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作者 刘维奇 史金凤 《统计研究》 CSSCI 北大核心 2006年第11期73-78,共6页
This paper introduces the theory of market efficiency simply and surveys various methods and results of week form market efficiency test of China.Then we test the sample and propose to test the week form market effici... This paper introduces the theory of market efficiency simply and surveys various methods and results of week form market efficiency test of China.Then we test the sample and propose to test the week form market efficiency test of China using the wild bootstrap variance ratio test which has been found to exhibit better small sample properties.The results are conducted with moving sub-sample windows and found that Shanghai market has been efficient of week form but Shenzhen market hasn’t been efficiency of week form. 展开更多
关键词 市场有效性 方差比检验 wild BOOTSTRAP方法
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WILD:基于加权信息损耗的离散化算法 被引量:8
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作者 李刚 李霁伦 童兆页 《南京大学学报(自然科学版)》 CAS CSCD 北大核心 2001年第2期148-153,共6页
现实应用中常常涉及许多连续的数值属性 ,而目前许多机器学习算法则要求所处理的属性具有离散值 .基于信息论的基本原理 ,提出一种新的有监督离散化算法WILD ,该算它可以看成是决策树离散化算法的一种扩充 ,其主要改进在于考虑区间内观... 现实应用中常常涉及许多连续的数值属性 ,而目前许多机器学习算法则要求所处理的属性具有离散值 .基于信息论的基本原理 ,提出一种新的有监督离散化算法WILD ,该算它可以看成是决策树离散化算法的一种扩充 ,其主要改进在于考虑区间内观测值出现的频度 ,采用加权信息损耗作为区间离散化的测度 ,以克服决策树算法离散不均衡的问题 .该算法非常自然地采用了自底向上的区间归并方案 ,可以同时归并多个相邻区间 ,有利于提高离散化算法的速度 .实验结果表明该算法能够提高机器学习算法的精度 . 展开更多
关键词 机器学习 离散化 加权信息损耗 wild 决策树 有监督算法
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基于Wild Bootstrap方差比检验的REITs市场有效性研究——以香港为例 被引量:3
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作者 张红 孙煦 《金融理论与实践》 北大核心 2015年第8期103-107,共5页
基于有效市场假说(EMH),使用Wild Bootstrap方差比检验法研究REITs市场的有效性。首先,阐述有效市场假说的基本原理,建立Wild Bootstrap方差比检验模型;之后,以香港为例,选取恒生REITs指数(HSRI)和恒生综合指数(HSCI),从纵、横向角度分... 基于有效市场假说(EMH),使用Wild Bootstrap方差比检验法研究REITs市场的有效性。首先,阐述有效市场假说的基本原理,建立Wild Bootstrap方差比检验模型;之后,以香港为例,选取恒生REITs指数(HSRI)和恒生综合指数(HSCI),从纵、横向角度分别进行总体和滑动方差比检验;最后,根据检验结果和实际情况判断REITs市场的有效性,得出研究结论和投资建议。在REITs市场有效性研究中引入了Wild Bootstrap方差比检验法,为相关研究提供了新的方法与研究视角。研究表明,香港REITs市场尚未达到弱式有效,市场有效性有待加强。 展开更多
关键词 REITS 市场有效性 方差比检验 wild BOOTSTRAP方法
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我国创业板市场弱式有效性的实证分析——基于Wild Bootstrap方差比检验 被引量:3
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作者 王红 陈帅 《商业时代》 北大核心 2014年第32期96-99,共4页
本文根据市场有效性假说,采用Wild Bootstrap方差比方法,基于创业板价格指数(399006)和创业板综合指数(399102),对我国创业板市场的有效性进行研究。研究结果表明,我国创业板市场具有弱式有效性。
关键词 我国创业板市场 弱式有效性 wild Bootstrap方差比检验
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