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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 08 December 2009, Vol.106(49), pp.20818-23
    Description: Duplication of genomic segments provides a primary resource for the origin of evolutionary novelties. However, most previous studies have focused on duplications of complete protein-coding genes, whereas little is known about the significance of duplication segments that are entirely internal to genes. Our examination of six fully sequenced genomes reveals that internal duplications of gene segments occur at a high frequency (0.001-0.013 duplications/gene per million years), similar to that of complete gene duplications, such that 8-17% of the genes in a genome carry duplicated intronic and/or exonic regions. At least 7-30% of such genes have acquired novel introns, either because a prior intron in the same gene has been duplicated, or more commonly, because a spatial change has activated a latent splice site. These results strongly suggest a major evolutionary role for internal gene duplications in the origin of genomic novelties, particularly as a mechanism for intron gain.
    Keywords: Gene Duplication ; Eukaryota -- Genetics ; Introns -- Genetics
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    Language: English
    In: Thin Solid Films, 2011, Vol.519(18), pp.5899-5904
    Description: Ni/NiO thin films for potential uses in batteries, fuel cells, sensors and supercapacitors were prepared by metallo-organic decomposition technique, using a unique solvent system of propionic acid (PPA) and amylamine (AA), in 0.5–2.0 molar ratios and 1 M Ni acetate precursor solute. This mixed solvent system exhibits ionic molecular clusters in solution, with nickel ions forming square planar coordinate complexes with the carboxylate groups, leading to easy film formation on spin coating at 3000 rpm and densification below 350 °C. Nano-sized (~ 50 nm), high surface area, low resistive (~ 600 nΩ m) Ni/NiO thin films were developed at a molar ratio of 1:1 AA/PPA using this methodology.
    Keywords: Nickel ; Nickel Oxide ; Thin Film ; Solvent ; Metallo-Organic Decomposition Process ; Engineering ; Physics
    ISSN: 0040-6090
    E-ISSN: 1879-2731
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  • 3
    Language: English
    In: Science (New York, N.Y.), 29 August 2014, Vol.345(6200), pp.1038-41
    Description: Subduction faults, called megathrusts, can generate large and hazardous earthquakes. The mode of slip and seismicity of a megathrust is controlled by the structural complexity of the fault zone. However, the relative strength of a megathrust based on the mode of slip is far from clear. The fault strength affects surface heat flow by frictional heating during slip. We model heat-flow data for a number of subduction zones to determine the fault strength. We find that smooth megathrusts that produce great earthquakes tend to be weaker and therefore dissipate less heat than geometrically rough megathrusts that slip mainly by creeping.
    Keywords: Plate Tectonics ; Earthquakes ; Fault Lines ; Seismology;
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 4
    In: Nature, 2017
    Description: Episodic tremor and accompanying slow slip, together called ETS, is most often observed in subduction zones of young and warm subducting slabs. ETS should help us to understand the mechanics of subduction megathrusts, but its mechanism is still unclear. It is commonly assumed that ETS represents a transition from seismic to aseismic behaviour of the megathrust with increasing depth, but this assumption is in contradiction with an observed spatial separation between the seismogenic zone and the ETS zone. Here we propose a unifying model for the necessary geological condition of ETS that explains the relationship between the two zones. By developing numerical thermal models, we examine the governing role of thermopetrologically controlled fault zone rheology (frictional versus viscous shear). High temperatures in the warm-slab environment cause the megathrust seismogenic zone to terminate before reaching the depth of the intersection of the continental Mohorovicic discontinuity (Moho) and the subduction interface, called the mantle wedge corner. High pore-fluid pressures around the mantle wedge corner give rise to an isolated friction zone responsible for ETS. Separating the two zones is a segment of semi-frictional or viscous behaviour. The new model reconciles a wide range of seemingly disparate observations and defines a conceptual framework for the study of slip behaviour and the seismogenesis of major faults.
    Keywords: Mexico ; Earthquakes ; Rheology ; Plate Tectonics ; Seismology;
    ISSN: 0028-0836
    E-ISSN: 1476-4687
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  • 5
    Language: English
    In: Neuron, 08 April 2015, Vol.86(1), pp.292-303
    Description: Although the coding transformation between visual thalamus and cortex has been known for over 50 years, whether a similar transformation occurs between auditory thalamus and cortex has remained elusive. Such a transformation may occur for time-varying sounds, such as music or speech. Most subcortical neurons explicitly encode the temporal structure of sounds with the temporal structure of their activity, but many auditory cortical neurons instead use a rate code. The mechanisms for this transformation from temporal code to rate code have remained unknown. Here we report that the membrane potential of rat auditory cortical neurons can show stimulus synchronization to rates up to 500 Hz, even when the spiking output does not. Synaptic inputs to rate-coding neurons arose in part from temporal-coding neurons but were transformed by voltage-dependent properties and push-pull excitatory-inhibitory interactions. This suggests that the transformation from temporal to rate code can be observed within individual cortical neurons. Gao and Wehr (2015) show that synaptic inputs to rate-coding neurons arise in part from temporal-coding neurons, but were transformed by push-pull excitatory-inhibitory interactions. This suggests that the transformation from temporal to rate code can be observed within individual cortical neurons.
    Keywords: Biology ; Anatomy & Physiology
    ISSN: 0896-6273
    E-ISSN: 1097-4199
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  • 6
    In: Nature, 2010, Vol.463(7282), p.828
    Description: In extremely acidic environments, enteric bacteria such as Escherichia coli rely on the amino acid antiporter AdiC to expel protons by exchanging intracellular agmatine ([Agm.sup.2+]) for extracellular arginine ([Arg.sup.+]) (1-3). AdiC is a representative member of the amino acid-polyamine-organocation (APC) superfamily of membrane transporters (4,5). The structure of substrate-free AdiC revealed a homodimeric assembly, with each protomer containing 12 transmembrane segments and existing in an outward-open conformation (6,7). The overall folding of AdiC is similar to that of the [Na.sup.+]-coupled symporters (8-11). Despite these advances, it remains unclear how the substrate (arginine or agmatine) is recognized and transported by AdiC. Here we report the crystal structure of an E. coli AdiC variant bound to Arg at 3.0 [Angstrom] resolution. The positively charged Arg is enclosed in an acidic binding chamber, with the head groups of Arg hydrogen-bonded to main chain atoms of AdiC and the aliphatic portion of Arg stacked by hydrophobic side chains of highly conserved residues. Arg binding induces pronounced structural rearrangement in transmembrane helix 6 (TM6) and, to a lesser extent, TM2 and TM10, resulting in an occluded conformation. Structural analysis identified three potential gates, involving four aromatic residues and Glu208, which may work in concert to differentially regulate the upload and release of Arg and Agm.
    Keywords: Glutamate -- Chemical Properties ; Glutamate -- Structure ; Arginine -- Chemical Properties ; Arginine -- Structure ; Escherichia Coli -- Chemical Properties ; Escherichia Coli -- Structure ; Membrane Proteins -- Research;
    ISSN: 0028-0836
    E-ISSN: 14764687
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  • 7
    Language: English
    In: Balkan Journal of Geometry and Its Applications, July, 2012, Vol.17(2), p.46(8)
    Description: In this paper, we consider the characterization of eigenfunctions for Laplacian operators on some Riemannian manifolds. Firstly we prove that for the space form ([M.sup.n.sub.K], [g.sub.K]) with the constant sectional curvature K, the first eigenvalue of Laplacian operator [[lambda].sub.1] ([M.sup.n.sub.K]) is greater than the limit of the first Dirichlet eigenvalue of Laplacian operator [[lambda].sup.D.sub.1] ([B.sub.K] (p, r)). Based on this, we then present a characterization of the Ricci soliton being an n-dim space form by the eigenfunctions corresponding to the first eigenvalue of Laplacian operator, which gives a generalization of an interesting result by Cheng in [3] from 2-dim to n-dim. Moreover, this result also gives a partly proof of a conjecture by Hamilton that a compact gradient shrinking Ricci soliton with positive curvature operator must be Einstein. M.S.C. 2010: 58G25, 35P05. Key words: Laplacian operator; Dirichlet eigenvalue; eigenfunction.
    Keywords: Eigenfunctions -- Research ; Laplace Transforms -- Research ; Operator Theory -- Research
    ISSN: 1224-2780
    E-ISSN: 18432875
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: Food Chemistry, Jan 15, 2014, Vol.143, p.307(6)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.foodchem.2013.07.127 Byline: Xiang Gao, Yiwen Yang, Yufeng Ai, Hongyi Luo, Baosheng Qiu Abstract: acents Longer storage results in darker solution colour or more release of pigments. acents Longer storage results in decreased Chl a and water-soluble sugars contents. acents Higher Fv/Fm value suggests better physiological recovery and quality. acents Sample treatment with 1mM K.sup.+ solution for Fv/Fm detection is cost-effective. Article History: Received 11 January 2013; Revised 22 July 2013; Accepted 25 July 2013
    Keywords: Chlorophyll -- Analysis ; Fluorescence -- Analysis
    ISSN: 0308-8146
    Source: Cengage Learning, Inc.
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  • 9
    Language: English
    In: Journal of Applied Physics, 15 November 2012, Vol.112(10)
    Description: Nanomaterials offer large reaction surfaces making for high-rate lithium-ion transfer and fewer constraints to avoid fracture. Nevertheless, surface effect arises inevitably due to so high surface-to-volume ratio. Accordingly, the fundamental framework of surface stress is involved to study diffusion-induced stresses within electrode nanoparticles in this work. As simple one-dimension models, solid and hollow nanowire electrode particles are investigated. The results show that surface tensile stress produces compressive stresses through the electrode materials, especially reducing maximum tensile stress, which may become a resistance to brittle fracture. Owing to high special surface area, it is demonstrated that diffusion-induced stresses for hollow materials are largely reduced compared to solid electrode materials. The influences of surface modulus on diffusion-induced stresses are much stronger under generalized plane strain condition in comparison with plane strain condition. Analysis based on the Tresca criterion indicates that shear failure may occur at the inner surface with decreasing radius.
    Keywords: Articles
    ISSN: 0021-8979
    E-ISSN: 1089-7550
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  • 10
    Language: English
    In: The Journal of organic chemistry, 02 March 2012, Vol.77(5), pp.2553-8
    Description: Aerobic oxidations of dianionic C(60) were examined in PhCN and PhCH(2)CN, where dioxygen was activated to O(2)(•-) via the single-electron transfer from C(60)(2-) and underwent oxygenation and dehydrogenation reactions, respectively. Addition of PhCH(2)Br led to further benzylation for the oxygenated product but not for the dehydrogenated one, suggesting that the initial two negative charges were preserved for the intermediates of the oxygenation reaction but not for those of the dehydrogenation reaction.
    Keywords: Acetonitriles -- Chemistry ; Fullerenes -- Chemistry ; Nitriles -- Chemistry ; Oxygen -- Chemistry
    ISSN: 00223263
    E-ISSN: 1520-6904
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