153 research outputs found

    Poetry Curriculum

    Get PDF
    The purpose of this project is to aid the classroom teacher in exposing children to poetry through a curriculum guide with enabling activities which will encourage children to develop an appreciation and understanding of poetry

    Gas permeation through a polymer network

    Full text link
    We study the diffusion of gas molecules through a two-dimensional network of polymers with the help of Monte Carlo simulations. The polymers are modeled as non-interacting random walks on the bonds of a two-dimensional square lattice, while the gas particles occupy the lattice cells. When a particle attempts to jump to a nearest-neighbor empty cell, it has to overcome an energy barrier which is determined by the number of polymer segments on the bond separating the two cells. We investigate the gas current JJ as a function of the mean segment density ρ\rho, the polymer length \ell and the probability qmq^{m} for hopping across mm segments. Whereas JJ decreases monotonically with ρ\rho for fixed \ell, its behavior for fixed ρ\rho and increasing \ell depends strongly on qq. For small, non-zero qq, JJ appears to increase slowly with \ell. In contrast, for q=0q=0, it is dominated by the underlying percolation problem and can be non-monotonic. We provide heuristic arguments to put these interesting phenomena into context.Comment: Dedicated to Lothar Schaefer on the occasion of his 60th birthday. 11 pages, 3 figure

    Simulation studies of permeation through two-dimensional ideal polymer networks

    Full text link
    We study the diffusion process through an ideal polymer network, using numerical methods. Polymers are modeled by random walks on the bonds of a two-dimensional square lattice. Molecules occupy the lattice cells and may jump to the nearest-neighbor cells, with probability determined by the occupation of the bond separating the two cells. Subjected to a concentration gradient across the system, a constant average current flows in the steady state. Its behavior appears to be a non-trivial function of polymer length, mass density and temperature, for which we offer qualitative explanations.Comment: 8 pages, 4 figure

    Embedded-grid silver transparent electrodes fabricated by selective metal condensation

    Get PDF
    We report a new materials system for the fabrication of embedded silver grid electrodes with micron-sized linewidth >10 times narrower than can be achieved using the conventional printing techniques of screen, inject and flexographic printing. Using micro-contact printed thin films of the highly fluorinated polymer poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate) together with low temperature heating of the substrate during metal deposition by thermal evaporation, we have fabricated embedded silver transparent grid electrodes on flexible plastic substrates without the need for a metal etching step or a separate grid-embedding step. This simplified approach to grid electrode fabrication is made possible by the very low condensation coefficient of Ag on areas of the substrate covered with the printed organofluorine layer, removing the need for harmful chemical etchants and slow chemical intensive electrochemical deposition steps

    Securing a bioenergy future without imports

    Get PDF
    The UK has legally binding renewable energy and greenhouse gas targets. Energy from biomass is anticipated to make major contributions to these. However there are concerns about the availability and sustainability of biomass for the bioenergy sector. A Biomass Resource Model has been developed that reflects the key biomass supply-chain dynamics and interactions determining resource availability, taking into account climate, food, land and other constraints. The model has been applied to the UK, developing four biomass resource scenarios to analyse resource availability and energy generation potential within different contexts. The model shows that indigenous biomass resources and energy crops could service up to 44% of UK energy demand by 2050 without impacting food systems. The scenarios show, residues from agriculture, forestry and industry provide the most robust resource, potentially providing up to 6.5% of primary energy demand by 2050. Waste resources are found to potentially provide up to 15.4% and specifically grown biomass and energy crops up to 22% of demand. The UK is therefore projected to have significant indigenous biomass resources to meet its targets. However the dominant biomass resource opportunities identified in the paper are not consistent with current UK bioenergy strategies, risking biomass deficit despite resource abundance

    Schwerpunkt: Rechtsextremismus und Soziale Arbeit

    Get PDF
    Das SI:SO-Heft widmet sich den folgenden Fragen: - Unter welchen Gesichtspunkten lassen sich Rechtspopulismus und Rechtsextremismus differenziert diskutieren? - Wie werden Rechtsextreme bestimmt und Rechtsextremismus identifiziert? - Inwiefern ist Soziale Arbeit von Rechtsextremismus und Rechtspopulismus betroffen? - Welche Kritiken gelten als zulässig, welche nicht und welche Auseinandersetzungen werden in der Sozialen Arbeit gemieden? - Welche politischen und zivilgesellschaftlichen Beiträge leistet Soziale Arbeit im Phänomenbereich Rechtsextremismus und Rechtspopulismus? - Welche Folgen ergeben sich für Hochschulen und Studium im Umgang mit Rechtsextremismus und Rechtspopulismus

    A non-canonical RNA silencing pathway promotes mRNA degradation in basal fungi

    Get PDF
    The increasing knowledge on the functional relevance of endogenous small RNAs (esRNAs) as riboregulators has stimulated the identification and characterization of these molecules in numerous eukaryotes. In the basal fungus Mucor circinelloides, an emerging opportunistic human pathogen, esRNAs that regulate the expression of many protein coding genes have been described. These esRNAs share common machinery for their biogenesis consisting of an RNase III endonuclease Dicer, a single Argonaute protein and two RNA-dependent RNA polymerases. We show in this study that, besides participating in this canonical dicer-dependent RNA interference (RNAi) pathway, the rdrp genes are involved in a novel dicer-independent degradation process of endogenous mRNAs. The analysis of esRNAs accumulated in wild type and silencing mutants demonstrates that this new rdrp-dependent dicer-independent regulatory pathway, which does not produce sRNA molecules of discrete sizes, controls the expression of target genes promoting the specific degradation of mRNAs by a previously unknown RNase. This pathway mainly regulates conserved genes involved in metabolism and cellular processes and signaling, such as those required for heme biosynthesis, and controls responses to specific environmental signals. Searching the Mucor genome for candidate RNases to participate in this pathway, and functional analysis of the corresponding knockout mutants, identified a new protein, R3B2. This RNase III-like protein presents unique domain architecture, it is specifically found in basal fungi and, besides its relevant role in the rdrp-dependent dicer-independent pathway, it is also involved in the canonical dicer-dependent RNAi pathway, highlighting its crucial role in the biogenesis and function of regulatory esRNAs. The involvement of RdRPs in RNA degradation could represent the first evolutionary step towards the development of an RNAi mechanism and constitutes a genetic link between mRNA degradation and post-transcriptional gene silencing
    corecore