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Träfflista för sökning "WFRF:(Liu Shiping) "

Sökning: WFRF:(Liu Shiping)

  • Resultat 1-6 av 6
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1.
  • Jarvis, Erich D., et al. (författare)
  • Whole-genome analyses resolve early branches in the tree of life of modern birds
  • 2014
  • Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 346:6215, s. 1320-1331
  • Tidskriftsartikel (refereegranskat)abstract
    • To better determine the history of modern birds, we performed a genome-scale phylogenetic analysis of 48 species representing all orders of Neoaves using phylogenomic methods created to handle genome-scale data. We recovered a highly resolved tree that confirms previously controversial sister or close relationships. We identified the first divergence in Neoaves, two groups we named Passerea and Columbea, representing independent lineages of diverse and convergently evolved land and water bird species. Among Passerea, we infer the common ancestor of core landbirds to have been an apex predator and confirm independent gains of vocal learning. Among Columbea, we identify pigeons and flamingoes as belonging to sister clades. Even with whole genomes, some of the earliest branches in Neoaves proved challenging to resolve, which was best explained by massive protein-coding sequence convergence and high levels of incomplete lineage sorting that occurred during a rapid radiation after the Cretaceous-Paleogene mass extinction event about 66 million years ago.
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2.
  • Li, Cai, et al. (författare)
  • Two Antarctic penguin genomes reveal insights into their evolutionary history and molecular changes related to the Antarctic environment
  • 2014
  • Ingår i: GigaScience. - 2047-217X .- 2047-217X. ; 3
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Penguins are flightless aquatic birds widely distributed in the Southern Hemisphere. The distinctive morphological and physiological features of penguins allow them to live an aquatic life, and some of them have successfully adapted to the hostile environments in Antarctica. To study the phylogenetic and population history of penguins and the molecular basis of their adaptations to Antarctica, we sequenced the genomes of the two Antarctic dwelling penguin species, the Adelie penguin [Pygoscelis adeliae] and emperor penguin [Aptenodytes forsteri]. Results: Phylogenetic dating suggests that early penguins arose similar to 60 million years ago, coinciding with a period of global warming. Analysis of effective population sizes reveals that the two penguin species experienced population expansions from similar to 1 million years ago to similar to 100 thousand years ago, but responded differently to the climatic cooling of the last glacial period. Comparative genomic analyses with other available avian genomes identified molecular changes in genes related to epidermal structure, phototransduction, lipid metabolism, and forelimb morphology. Conclusions: Our sequencing and initial analyses of the first two penguin genomes provide insights into the timing of penguin origin, fluctuations in effective population sizes of the two penguin species over the past 10 million years, and the potential associations between these biological patterns and global climate change. The molecular changes compared with other avian genomes reflect both shared and diverse adaptations of the two penguin species to the Antarctic environment.
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3.
  • Zhang, Guojie, et al. (författare)
  • Comparative genomics reveals insights into avian genome evolution and adaptation
  • 2014
  • Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 346:6215, s. 1311-1320
  • Tidskriftsartikel (refereegranskat)abstract
    • Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits.
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4.
  • Hu, Xing, et al. (författare)
  • Dynamic Channel Slot Allocation Scheme and Performance Analysis of Cyclic Quorum Multichannel MAC Protocol
  • 2017
  • Ingår i: Mathematical problems in engineering (Print). - : HINDAWI LTD. - 1024-123X .- 1563-5147.
  • Tidskriftsartikel (refereegranskat)abstract
    • In high diversity node situation, multichannel MAC protocol can improve the frequency efficiency, owing to fewer collisions compared with single-channel MAC protocol. And the performance of cyclic quorum-based multichannel (CQM) MAC protocol is outstanding. Based on cyclic quorum system and channel slot allocation, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQMMAC protocol, a Markov chain model, which combines the channel-hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm. In addition, to improve the performance of CQM protocol in unsaturation situation, a dynamic channel slot allocation of CQM(DCQM) protocol is proposed, based on wavelet neural network. Finally, the performance of CQM protocol and DCQM protocol is simulated by Qualnet platform. And the simulation results show that the analytic and simulation results match very well; the DCQM performs better in unsaturation situation.
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5.
  • Huang, Tianyu, et al. (författare)
  • 2D autoregressive model-based dynamic correlated massive MU-MIMO channel simulator
  • 2017
  • Ingår i: Electronics Letters. - : INST ENGINEERING TECHNOLOGY-IET. - 0013-5194 .- 1350-911X. ; 53:17
  • Tidskriftsartikel (refereegranskat)abstract
    • To design a dynamic correlated channel simulator which can precisely depict the space-time correlation properties and be suitable for the massive multi-user multiple-input multiple-output (MU-MIMO) system, a 2D autoregressive (2D AR) model-based method is proposed. Specifically, by exploiting stationarity in space-time domain, the authors use 2D AR method to create the space-time channel matrices of every user separately. In this way, the space-time dimension of the simulated channel can be modified flexibly without rebuilding the 2D AR model, and spatial correlation matrix with excessively big size is not necessary to guarantee the accuracy of the proposed simulator, making it suitable for massive MU-MIMO system. Simulation results verify the advantages of the proposed simulator.
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6.
  • Liu, Shiping, et al. (författare)
  • Population Genomics Reveal Recent Speciation and Rapid Evolutionary Adaptation in Polar Bears
  • 2014
  • Ingår i: ; 157:4, s. 785-794
  • Tidskriftsartikel (refereegranskat)abstract
    • Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyper-lipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show that the species diverged only 479-343 thousand years BP. We find that genes on the polar bear lineage have been under stronger positive selection than in brown bears; nine of the top 16 genes under strong positive selection are associated with cardiomyopathy and vascular disease, implying important reorganization of the cardiovascular system. One of the genes showing the strongest evidence of selection, APOB, encodes the primary lipoprotein component of low-density lipoprotein (LDL); functional mutations in APOB may explain how polar bears are able to cope with life-long elevated LDL levels that are associated with high risk of heart disease in humans.
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  • Resultat 1-6 av 6
 
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