36,439 research outputs found

    Speaking Up: Opening Dialogue with Pre-service and In-service Teachers about Reading Children’s Books Inclusive of Lesbian and Gay Families

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    One of the best ways to include all family structures in classroom practice is through children‘s literature. While more and more quality books depicting family diversity, inclusive of gay and lesbian families, are published every year, it is often the unknown discourse surrounding such readings and the unknown support of the teacher that keeps these books from even entering preschool through grade four classrooms

    Soft versus Hard X-ray emission in AGN: partial covering and warm plus cold absorber models

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    We analyse the ROSAT PSPC hardness ratio and the 0.5-2 keV to 2-10 keV flux ratio of 65 Active Galactic Nuclei (AGN) for which there are both ROSAT archival observations available and 2-10 keV fluxes, mostly from the HEAO-1 MC-LASS survey. We conclude that the simplest spectral model for the AGN that can accommodate the variety of X-ray colours obtained is a standard power law (with energy spectral index α∼0.9\alpha\sim 0.9) plus a ∼0.1\sim 0.1 keV black body both partially absorbed. In our sample, type 1 AGN require an absorbing column around 1022 cm−210^{22}\, {\rm cm}^{-2} with covering fractions between 20 and 100\%, while type 2 AGN display larger columns and ∼100%\sim 100\% coverage. This simple model also provides a good link between soft and hard AGN X-ray luminosity functions and source counts. We also consider a warm absorber as an alternative model to partial covering and find that the the presence of gas in two phases (ionized and neutral) is required.Comment: 10 pages, Latex (mn.sty), 1 table, 5 figures included (epsf), postscript version also available via anonymous ftp at ftp://astsun1.unican.es/pub/ceballos/ . Accepted for publication in MNRA

    Presentations for monoids of finite partial isometries

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    In this paper we give presentations for the monoid DPn\mathcal{DP}_n of all partial isometries on {1,…,n}\{1,\ldots,n\} and for its submonoid ODPn\mathcal{ODP}_n of all order-preserving partial isometries.Comment: 11 pages, submitte

    Position Effect Takes Precedence Over Target Sequence in Determination of Adenine Methylation Patterns in the Nuclear Genome of a Eukaryote, \u3cem\u3eTetrahymena thermophila\u3c/em\u3e

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    Approximately 0.8% of the adenine residues in the macronuclear DNA of the ciliated protozoan Tetrahymena thermophila are modified to N6-methyladenine. DNA methylation is site specific and the pattern of methylation is constant between clonal cell lines. In vivo, modification of adenine residues appears to occur exclusively in the sequence 5′-NAT-3′, but no consensus sequence for modified sites has been found. In this study, DNA fragments containing a site that is uniformly methylated on the 50 copies of the macronuclear chromosome were cloned into the extrachromosomal rDNA. In the novel location on the rDNA minichromosome, the site was unmethylated. The result was the same whether the sequences were introduced in a methylated or unmethylated state and regardless of the orientation of the sequence with respect to the origin of DNA replication. The data show that sequence is insufficient to account for site-specific methylation in Tetrahymena and argue that other factors determine the pattern of DNA methylation

    Asymptotic behaviour for a class of non-monotone delay differential systems with applications

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    The paper concerns a class of nn-dimensional non-autonomous delay differential equations obtained by adding a non-monotone delayed perturbation to a linear homogeneous cooperative system of ordinary differential equations. This family covers a wide set of models used in structured population dynamics. By exploiting the stability and the monotone character of the linear ODE, we establish sufficient conditions for both the extinction of all the populations and the permanence of the system. In the case of DDEs with autonomous coefficients (but possible time-varying delays), sharp results are obtained, even in the case of a reducible community matrix. As a sub-product, our results improve some criteria for autonomous systems published in recent literature. As an important illustration, the extinction, persistence and permanence of a non-autonomous Nicholson system with patch structure and multiple time-dependent delays are analysed.Comment: 26 pages, J Dyn Diff Equat (2017

    Promoting nutrition sensitive and climate smart agriculture through increased use of traditional underutilised species in the Pacific

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    Poster presented at Tropentag 2014. International Conference on Research on Food Security, Natural Resource Management and Rural Development. "Bridging the Gap between Increasing Knowledge and Decreasing Resources" Prague (Czech Republic) Sep 17-19 2014
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