4,488 research outputs found

    RNA-seq reveals post-transcriptional regulation of Drosophila insulin-like peptide dilp8 and the neuropeptide-like precursor Nplp2 by the exoribonuclease Pacman/XRN1

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    Ribonucleases are critically important in many cellular and developmental processes and defects in their expression are associated with human disease. Pacman/XRN1 is a highly conserved cytoplasmic exoribonuclease which degrades RNAs in a 5' - 3' direction. In Drosophila, null mutations in pacman result in small imaginal discs, a delay in onset of pupariation and lethality during the early pupal stage. In this paper, we have used RNA-seq in a genome-wide search for mRNAs misregulated in pacman null wing imaginal discs. Only 4.2% of genes are misregulated ±>2-fold in pacman null mutants compared to controls, in line with previous work showing that Pacman has specificity for particular mRNAs. Further analysis of the most upregulated mRNAs showed that Pacman post-transcriptionally regulates the expression of the secreted insulin-like peptide Dilp8. Dilp8 is related to human IGF-1, and has been shown to co-ordinate tissue growth with developmental timing in Drosophila. The increased expression of Dilp8 is consistent with the developmental delay seen in pacman null mutants. Our analysis, together with our previous results, show that the normal role of this exoribonuclease in imaginal discs is to suppress the expression of transcripts that are crucial in apoptosis and growth control during normal development

    Avian Frugivory in a Fruiting Mulberry Tree (Morus rubra) in Arkansas

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    A fruiting Mulberry tree (Morus rubra) was observed for 67 hours in the spring of 2016 and 2017 in Fort Smith, Arkansas. A total of 172 five-minute scans were performed, during which the following parameters were recorded: species visited, number of individuals of each species, time of visitations, and foraging tier. Between each scan, the foraging rate (number of fruits consumed/min) and inter- and intra- specific aggressive interactions were recorded. A total of 3465 observations of individual birds from 32 species was recorded. Species diversity index was higher in the upper half of the tree. The mean foraging rates for the 6 most commonly observed species ranged from 1.2-2.3 fruits/min. A total of 346 aggressive interactions was observed of which 68% were intraspecific

    Logarithmically-concave moment measures I

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    We discuss a certain Riemannian metric, related to the toric Kahler-Einstein equation, that is associated in a linearly-invariant manner with a given log-concave measure in R^n. We use this metric in order to bound the second derivatives of the solution to the toric Kahler-Einstein equation, and in order to obtain spectral-gap estimates similar to those of Payne and Weinberger.Comment: 27 page

    Preparation of Al2O3 - SiC In-Situ Composite Powder Mixtures by Carbothermal Reduction of Kaolinite

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    A1,,O3-SiC,, composite powder mixtures were prepared by carbothermal reduction of kaolinite (A],03.2SiO,.2H,O) in argon atmosphere at constant gas pressure of 0.15 MPa. The reactions were carried out with different mole ratios of silica (in the precursor) and carbon (4.5-9.0), with two types of carbon i.e.carbon black (300m2/g)and activated charcoal (1000m2/g) and at different temperatures in the temperature range of 1550-17000C with one hour of soaking to find the progress of the reaction in all the cases. It was observed that the reactions were complete at 17000C. The reactions were carried out with higher soaking time to optimise the process. It was noted that mullite forms as the intermediate phase at lower temperatures which converts progressively later to a mixture of A1,O, and SiC,, composite product at higher temperatures

    Nonequilibrium stationary states of harmonic chains with bulk noises

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    We consider a chain composed of NN coupled harmonic oscillators in contact with heat baths at temperature Tâ„“T_\ell and TrT_r at sites 1 and NN respectively. The oscillators are also subjected to non-momentum conserving bulk stochastic noises. These make the heat conductivity satisfy Fourier's law. Here we describe some new results about the hydrodynamical equations for typical macroscopic energy and displacement profiles, as well as their fluctuations and large deviations, in two simple models of this type.Peer reviewe

    Lattice Boltzmann Model for Axisymmetric Multiphase Flows

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    In this paper, a lattice Boltzmann (LB) model is presented for axisymmetric multiphase flows. Source terms are added to a two-dimensional standard lattice Boltzmann equation (LBE) for multiphase flows such that the emergent dynamics can be transformed into the axisymmetric cylindrical coordinate system. The source terms are temporally and spatially dependent and represent the axisymmetric contribution of the order parameter of fluid phases and inertial, viscous and surface tension forces. A model which is effectively explicit and second order is obtained. This is achieved by taking into account the discrete lattice effects in the Chapman-Enskog multiscale analysis, so that the macroscopic axisymmetric mass and momentum equations for multiphase flows are recovered self-consistently. The model is extended to incorporate reduced compressibility effects. Axisymmetric equilibrium drop formation and oscillations, breakup and formation of satellite droplets from viscous liquid cylindrical jets through Rayleigh capillary instability and drop collisions are presented. Comparisons of the computed results with available data show satisfactory agreement.Comment: 17 pages, 11 figures, to be published in Physical Review

    Reconstruction of protein structures from a vectorial representation

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    We show that the contact map of the native structure of globular proteins can be reconstructed starting from the sole knowledge of the contact map's principal eigenvector, and present an exact algorithm for this purpose. Our algorithm yields a unique contact map for all 221 globular structures of PDBselect25 of length N≤120N \le 120. We also show that the reconstructed contact maps allow in turn for the accurate reconstruction of the three-dimensional structure. These results indicate that the reduced vectorial representation provided by the principal eigenvector of the contact map is equivalent to the protein structure itself. This representation is expected to provide a useful tool in bioinformatics algorithms for protein structure comparison and alignment, as well as a promising intermediate step towards protein structure prediction.Comment: 4 pages, 1 figur
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