54 research outputs found

    Long run value stabilization in a real options perspective

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    The present value of growth opportunities with stable long run value and decreasing investment cost is addressed in a real options perspective. The model is solved in terms of closed form solutions, and a duality between elementary real options of waiting to invest is conjectured to be a fundamental structure of a forthcoming theory of real options. A pure capital budgeting perspective is pursued. Natural lines for future research are accounted for.PVGO, real options, strategic investment, learning

    Two and three loops computations of renormalization constants for lattice QCD

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    Renormalization constants can be computed by means of Numerical Stochastic Perturbation Theory to two/three loops in lattice perturbation theory, both in the quenched approximation and in the full (unquenched) theory. As a case of study we report on the computation of renormalization constants of the propagator for Wilson fermions. We present our unquenched (N_f=2) computations and compare the results with non perturbative determinations.Comment: Lattice2004(improv), 3 pages, 4 figure

    3-d Lattice QCD Free Energy to Four Loops

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    We compute the expansion of the 3-d Lattice QCD free energy to four loop order by means of Numerical Stochastic Perturbation Theory. The first and second order are already known and are correctly reproduced. The third and fourth order coefficients are new results. The known logarithmic divergence in the fourth order is correctly identified. We comment on the relevance of our computation in the context of dimensionally reduced finite temperature QCD.Comment: 8 pages, 3 figures, latex typeset with JHEP3.cl

    3-d lattice SU(3) free energy to four loops

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    We report on the perturbative computation of the 3d lattice Yang-Mills free energy to four loops by means of Numerical Stochastic Perturbation Theory. The known first and second orders have been correctly reproduced; the third and fourth order coefficients are new results and the known logarithmic IR divergence in the fourth order has been correctly identified. Progress is being made in switching to the gluon mass IR regularization and the related inclusion of the Faddeev-Popov determinant.Comment: Lattice2004(non-zero), 3 pages, 2 figure

    Four loop stochastic perturbation theory in 3d SU(3)

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    Dimensional reduction is a key issue in finite temperature field theory. For example, when following the QCD Free Energy from low to high scales across the critical temperature, ultrasoft degrees of freedom can be captured by a 3d SU(3) pure gauge theory. For such a theory a complete perturbative matching requires four loop computations, which we undertook by means of Numerical Stochastic Perturbation Theory. We report on the computation of the pure gauge plaquette in 3d, and in particular on the extraction of the logarithmic divergence at order g^8, which had already been computed in the continuum.Comment: 3 pages, 2 figure, Lattice2003(nonzero

    Composition, potential emissions and agricultural value of pig slurry from Spanish commercial farms

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    [EN] Pig slurry is a valuable fertilizer for crop production but at the same time its management may pose environmental risks. Slurry samples were collected from 77 commercial farms of four animal categories (gestating and lactating sows, nursery piglets and growing pigs) and analyzed for macronutrients, micronutrients, heavy metals and volatile fatty acids. Emissions of ammonia (NH3) and biochemical methane potential (BMP) were quantified. Slurry electrical conductivity, pH, dry matter content and ash content were also determined. Data analysis included an analysis of correlations among variables, the development of predictionmodels for gaseousemissions and the analysis of nutritional content of slurries for crop production. Descriptive information is provided in this work and shows a wide range of variability in all studied variables. Animal category affected some physicochemical parameters, probably as a consequence of different slurry management and use of cleaning water. Slurries from gestating sows and growing pigs tended to be more concentrated in nutrients, whereas the slurry from lactating sows and nursery piglets tended to be more diluted. Relevant relationships were found among slurry characteristics expressed in fresh basis and gas emissions. Predictivemodels using on-farmmeasurable parameterswere obtained forNH3 (R2 = 0.51) andCH4 (R2 = 0.76), which suggests that BMP may be estimated in commercial farms from easily determined slurry characteristics. Finally, slurry nutrient composition was highly variable. Therefore, complete analyses of slurries should be performed for an effective and environmental friendly land application.This project was funded by the Spanish Ministry of Science and Innovation (AGL2011-30023) and the Valencian Government (ACOMP/2013/118). We thank the BABEL Project, Building Academic Bonds between Europe and Latin America. Erasmus Mundus Programme Action 2 for PhD fellowships. 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    The «Emilian Model» for the Twenty-First Century

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    The main purpose of this paper is to update the analysis of the «Emilian model». For decades, this Model has been the topic of many debates well beyond the Italian boundaries, mainly because of its ability to balance efficiency (e.g. productivity) and equity (e.g. social cohesion). Top ranking Region both at national and European level, the Emilia-Romagna economic system is undergoing a real «Metamorphosis», as pointed out in the 2008 EUNIP contribution. Now, three case studies enable us to shed light on this process of change: the industrial districts - or clusters - of Carpi (textile/clothing), Sassuolo (ceramic tiles), and Reggio Emilia (mechatronics). In particular, this change amounts to the rise of medium-sized enterprises, which are in a better position to manage upstream and downstream activities (e.g., R&D, design, marketing, etc.) involving fixed costs. A series of remarks about the New Industrial Policy envisaged by D. Rodrik in his seminal papers completes our analysis. In the Knowledge Era we advocate stronger cooperation between local authorities, universities and private firms

    Preliminary results in unquenched Numerical Stochastic Perturbation Theory

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    Introducing fermionic loops contributions in Numerical Stochastic Perturbation Theory was mainly motivated by the proposal to compute 2-3 loops for renormalization constants (and improvement coefficients). This is feasible because the computational overhead of unquenching NSPT is by far lower than for non perturbative simulations. We report on first, preliminary results for the quark propagator (basically the third loop for the critical mass) and discuss the status of the computation of other quantities
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