743 research outputs found

    Support to organic farming and bio-energy as rural development drivers

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    The paper conducts an analysis of the potentials of organic farming and bioenergy as win-win-win strategies promoting economic growth, employment and the environment at the same time. Empirical evidence does not indicate that conversion to organic farming will enhance economic growth and employment, but there are environmental benefits primarily due to the absence of pesticides. If energy crops are grown on idle land bioenergy has the potential of generating economic activities and employment alongside with CO2 reductions. Liquid biofuel production is a relatively expensive way of reducing CO2, but there is a potential for technological breakthroughs making it economically viable to use low value feedstock like straw and waste for bioethanol production. It is recommended that the positive environmental effects of organic farming and bioenergy are internalised through green taxes on the negative externalities from conventional farming and fossil energy use

    From the macroscopic to the microscopic: some scientific insights

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    The full report in which this chapter appears is in ORE: http://hdl.handle.net/10871/1416

    Thermodynamics of O(N) sigma models: 1/N corrections

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    The thermodynamics of the O(N) linear and nonlinear sigma models in 3+1 dimensions is studied. We calculate the pressure to next-to-leading order in the 1/N expansion and show that at this order, temperature-independent renormalization is only possible at the minimum of the effective potential. The 1/N expansion is found to be a good expansion for N as low as 4, which is the case relevant for low-energy QCD phenomenology. We consider the cases with and without explicit symmetry breaking. We show that previous next-to-leading order calculations of the pressure are either breaking down in the temperatures of interest, or based on unjustifiable high-energy approximations.Comment: 11 pages, 5 figures, revte

    Mass Expansions of Screened Perturbation Theory

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    The thermodynamics of massless phi^4-theory is studied within screened perturbation theory (SPT). In this method the perturbative expansion is reorganized by adding and subtracting a mass term in the Lagrangian. We analytically calculate the pressure and entropy to three-loop order and the screening mass to two-loop order, expanding in powers of m/T. The truncated m/T-expansion results are compared with numerical SPT results for the pressure, entropy and screening mass which are accurate to all orders in m/T. It is shown that the m/T-expansion converges quickly and provides an accurate description of the thermodynamic functions for large values of the coupling constant.Comment: 22 pages, 10 figure

    Identification of miRNA targets with stable isotope labeling by amino acids in cell culture

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    miRNAs are small noncoding RNAs that regulate gene expression. We have used stable isotope labeling by amino acids in cell culture (SILAC) to investigate the effect of miRNA-1 on the HeLa cell proteome. Expression of 12 out of 504 investigated proteins was repressed by miRNA-1 transfection. This repressed set of genes significantly overlaps with miRNA-1 regulated genes that have been identified with DNA array technology and are predicted by computational methods. Moreover, we find that the 3′-untranslated region for the repressed set are enriched in miRNA-1 complementary sites. Our findings demonstrate that SILAC can be used for miRNA target identification and that one highly expressed miRNA can regulate the levels of many different proteins

    Eclipsing Binaries in Open Clusters

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    Detached eclipsing binaries are very useful objects for calibrating theoretical stellar models and checking their predictions. Detached eclipsing binaries in open clusters are particularly important because of the additional constraints on their age and chemical composition from their membership of the cluster. I compile a list containing absolute parameters of well-studied eclipsing binaries in open clusters, and present new observational data on the B-type systems V1481 Cyg and V2263 Cyg which are members of the young open cluster NGC 7128.Comment: 4 pages, 2 colour figures. Poster presentation for IAUS 240 (Binary Stars as Critical Tools and Tests in Contemporary Astrophysics), Prague, August 2006. The poster itself can be dowloaded in ppt and pdf versions from http://www.astro.keele.ac.uk/~jkt/pubs.htm
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