22,391 research outputs found

    Real decoupling ghost quantization of the CGHS model for two dimensional black holes

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    A complete RST quantization of a CGHS model plus Strominger term is carried out. In so doing a conformal invariant theory with Îş=N12\kappa=\frac{N}{12} is found, that is, without ghosts contribution. The physical consequences of the model are analysed and positive definite Hawking radiation is found.Comment: 14 pages, latex, no figures, marginal errors correcte

    The 3'-untranslated region directs ribosomal protein-encoding mRNAs to specific cytoplasmic regions

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    mRNA localization is a conserved post-transcriptional process crucial for a variety of systems. We have analyzed the subcellular distribution of mRNAs encoding human cytosolic and mitochondrial ribosomal proteins. Biochemical fractionation experiments showed that the transcripts for cytosolic ribosomal proteins associate preferentially with the cytoskeleton via actin microfilaments. Transfection in HeLa cells of a GFP reporter construct containing the cytosolic ribosomal protein L4 3'-UTR showed that the 3'-UTR is necessary for the association of the transcript to the cytoskeleton. Using confocal analysis we demonstrate that the chimeric transcript is specifically associated with the perinuclear cytoskeleton. We also show that mRNA for mitochondrial ribosomal protein S12 is asymmetrically distributed in the cytoplasm. In fact, this transcript was localized mainly in the proximity of mitochondria, and the localization was 3'-UTR-dependent. In summary, ribosomal protein mRNAs constitute a new class of localized transcripts that share a common localization mechanism

    Conformal invariance in 2-dimensional discrete field theory

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    A discretized massless wave equation in two dimensions, on an appropriately chosen square lattice, exactly reproduces the solutions of the corresponding continuous equations. We show that the reason for this exact solution property is the discrete analog of conformal invariance present in the model, and find more general field theories on a two-dimensional lattice that exactly solve their continuous limit equations. These theories describe in general non-linearly coupled bosonic and fermionic fields and are similar to the Wess-Zumino-Witten model.Comment: 18 pages, RevTeX, 2 figures included; revision of title and introductio

    Universality and Scaling at the Onset of Quantum Black Hole Formation

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    In certain two-dimensional models, collapsing matter forms a black hole if and only if the incoming energy flux exceeds the Hawking radiation rate. Near the critical threshold, the black hole mass is given by a universal formula in terms of the distance from criticality, and there exists a scaling solution describing the formation and evaporation of an arbitrarily small black hole.Comment: 9 pages, 3 figures (uuencoded

    The Italian Design Approach to Materials between tangible and intangible Meanings

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    This article deals with the Italian Design approach to Materials based on a long tradition of challenging exchanges between intellectual practices. Focusing on design and enterprises history, the authors, on the basis of their previous studies, explain the approach and the reasons of the osmotic process between technology and humanities in Italy, and how those challenging exchanges impacted on production as well as on further 80 Cuaderno 70 | Centro de Estudios en Diseño y Comunicación (2018). pp 67-80 ISSN 1668-0227 Marinella Ferrara and Anna Cecilia Russo The Italian Design Approach to Materials (...) developments. An overview of the European cultural landscape of the times helps to focus on the leading theories that still represent a stronghold of Design Humanities. Exploring the semiotic meaning of materials enhances the investigations on their applications as well as new, ongoing researches in the field of Material Design, also in terms of sustainability and interaction
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