13,089 research outputs found

    Short-term effects of new universities on regional innovation

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    This paper analyzes empirically the channels through which university research affects industry innovation. We examine how the opening of new science, medicine and engineering departments in Italy during 1985-2000 affected regional innovation systems. We find that creation of a new university department increased regional innovation activity 3-4 years later. On average, an opening of a new department in a region has led to a ten percent change in the number of patents filed by regional firms. Given that this effect occurs within the first half decade of the appearance of a new department, it cannot be ascribed to improvements in the quality and quantity of graduates. At the same time, traditional measures of academic research activity can explain only around 30 percent of this effect.Innovation, Academic Research, R&D, Universities, University-Industry Linkages, Technology Transfer, Regional Innovation Systems.

    Size effects and dislocation patterning in two-dimensional bending

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    We perform atomistic Monte Carlo simulations of bending a Lennard-Jones single crystal in two dimensions. Dislocations nucleate only at the free surface as there are no sources in the interior of the sample. When dislocations reach sufficient density, they spontaneously coalesce to nucleate grain boundaries, and the resulting microstructure depends strongly on the initial crystal orientation of the sample. In initial yield, we find a reverse size effect, in which larger samples show a higher scaled bending moment than smaller samples for a given strain and strain rate. This effect is associated with source-limited plasticity and high strain rate relative to dislocation mobility, and the size effect in initial yield disappears when we scale the data to account for strain rate effects. Once dislocations coalesce to form grain boundaries, the size effect reverses and we find that smaller crystals support a higher scaled bending moment than larger crystals. This finding is in qualitative agreement with experimental results. Finally, we observe an instability at the compressed crystal surface that suggests a novel mechanism for the formation of a hillock structure. The hillock is formed when a high angle grain boundary, after absorbing additional dislocations, becomes unstable and folds to form a new crystal grain that protrudes from the free surface.Comment: 15 pages, 8 figure

    Controllable binding of polar molecules and meta-stability of 1-D gases with attractive dipole forces

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    We explore one-dimensional (1-D) samples of ultracold polar molecules with attractive dipole-dipole interactions and show the existence of a repulsive barrier due to a strong quadrupole interaction between molecules. This barrier can stabilize a gas of ultracold KRb molecules and even lead to long-range wells supporting bound states between molecules. The properties of these wells can be controlled by external electric fields, allowing the formation of long polymer-like chains of KRb, and studies of quantum phase transitions by varying the effective interaction between molecules. We discuss the generalization of those results to other systems

    The thermal Hall effect of spin excitations in a Kagome magnet

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    At low temperatures, the thermal conductivity of spin excitations in a magnetic insulator can exceed that of phonons. However, because they are charge neutral, the spin waves are not expected to display a thermal Hall effect in a magnetic field. Recently, this semiclassical notion has been upended in quantum magnets in which the spin texture has a finite chirality. In the Kagome lattice, the chiral term generates a Berry curvature. This results in a thermal Hall conductivity Îşxy\kappa_{xy} that is topological in origin. Here we report observation of a large Îşxy\kappa_{xy} in the Kagome magnet Cu(1-3, bdc) which orders magnetically at 1.8 K. The observed Îşxy\kappa_{xy} undergoes a remarkable sign-reversal with changes in temperature or magnetic field, associated with sign alternation of the Chern flux between magnon bands. We show that thermal Hall experiments probe incisively the effect of Berry curvature on heat transport.Comment: 6 pages, 3 figure

    Description of nuclear systems with a self-consistent configuration-mixing approach. I: Theory, algorithm, and application to the 12^{12}C test nucleus

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    Although self-consistent multi-configuration methods have been used for decades to address the description of atomic and molecular many-body systems, only a few trials have been made in the context of nuclear structure. This work aims at the development of such an approach to describe in a unified way various types of correlations in nuclei, in a self-consistent manner where the mean-field is improved as correlations are introduced. The goal is to reconcile the usually set apart Shell-Model and Self-Consistent Mean-Field methods. This approach is referred as "variational multiparticle-multihole configuration mixing method". It is based on a double variational principle which yields a set of two coupled equations that determine at the same time the expansion coefficients of the many-body wave function and the single particle states. The formalism is derived and discussed in a general context, starting from a three-body Hamiltonian. Links to existing many-body techniques such as the formalism of Green's functions are established. First applications are done using the two-body D1S Gogny effective force. The numerical procedure is tested on the 12^{12}C nucleus in order to study the convergence features of the algorithm in different contexts. Ground state properties as well as single-particle quantities are analyzed, and the description of the first 2+2^+ state is examined. This study allows to validate our numerical algorithm and leads to encouraging results. In order to test the method further, we will realize in the second article of this series, a systematic description of more nuclei and observables obtained by applying the newly-developed numerical procedure with the same Gogny force. As raised in the present work, applications of the variational multiparticle-multihole configuration mixing method will however ultimately require the use of an extended and more constrained Gogny force.Comment: 22 pages, 18 figures, accepted for publication in Phys. Rev. C. v2: minor corrections and references adde

    The Value of Terroir: Hedonic Estimation of Vineyard Sale Prices

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    We examine the value of terroir, which refers to the special characteristics of a place that impart unique qualities to the wine produced. We do this by conducting a hedonic analysis of vineyard sales in the Willamette Valley of Oregon to ascertain whether site attributes, such as slope, aspect, elevation, and soil types, or designated appellations are more important determinants of price. We find that prices are strongly determined by sub-AVA appellation designations, but not by specific site attributes. These results indicate that the concept of terroir matters economically, although the reality of terroir--as proxied for by locational attributes--is not significant.
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