Reflection positive doubles

Here we introduce reflection positive doubles, a general framework for reflection positivity, covering a wide variety of systems in statistical physics and quantum field theory. These systems may be bosonic, fermionic, or parafermionic in nature. Within the framework of reflection positive doubles, we give necessary and sufficient conditions for reflection positivity. We use a reflection-invariant cone to implement our construction. Our characterization allows for a direct interpretation in terms of coupling constants, making it easy to check in concrete situations. We illustrate our methods with numerous examples

Market Demand, Technological Opportunity and Research Spillovers on R&D Intensity and Productivity Growth

This paper uses sales and patent distribution data to establish the market and technological "positions" of firms. A notion of technological proximity of firms is developed in order to quantify potential R&D spillovers. The importance of the position variables and the potential spilover pool in explaining R&D intensity, patent productivity and TFP growth is explored.I find that both technological and market positions are signifi-cant in explaining R&D intensity, and that the technological effects are significant in explaining patent productivity. I cannot distinguish between the two effects in explaining TFP growth. Spillovers are important in all three contexts. Firms in an area where there is a high level of research by other firms do more R&D themselves, they produce more patents per R&D dollar, and their productivity grows faster, even controlling for the increased R&D and patents. These effects are present controlling for both industry and technological position effects.

Technological Opportunity and Spillovers of R&D: Evidence from Firms' Patents, Profits and Market Value

This paper presents evidence that firms' patents, profits and market value are systematically related to the"technological position" of firms' research programs. Further, firms are seen to "move" in technology space in response to the pattern of contemporaneous profits at different positions. These movements tend to erode excess returns."Spillovers" of R&D are modelled by examining whether the R&D of neighboring firms in technology space has an observable impact on the firm's R&D success. Firms whose neighbors do much R&D produce more patents per dollar of their own R&D,with a positive interaction that gives high R&D firms the largest benefit from spillovers. In terms of profit and market value, however, their are both positive and negative effects of nearby firms' R&D. The net effect is positive for high R&D firms, but firms with R&D about one standard deviation below the mean are made worse off overall by the R&D of others.

Nano-scale oxygen octahedral tilting in 0.90(Bi1/2Na1/2)TiO3-0.05(Bi1/2K1/2)TiO3-0.05BaTiO3 lead-free perovskite piezoelectric ceramics

The oxygen octahedral tilted domains in 0.90(Bi1/2Na1/2)TiO3-0.5(Bi1/2K1/2)TiO3-0.5BaTiO3 lead-free perovskite piezoelectric ceramic have been studied by transmission electron microscopy (TEM). Selected-area electron diffraction patterns shows the 1/2ooo and 1/2ooe reflections, indicating the presence of antiphase (a-a-a-) and in-phase (aoaoc+) octahedral tilting, respectively. The morphology and distributions of these tilted domains are shown in the centered dark-field images. Further, the Bragg-filtered high-resolution TEM image reveals that the size of the in-phase tilted domains varies from 1 to 8 nm across. The ceramic contains the mixture of non-tilted and variants of the antiphase and in-phase tilted domains.Comment: 12 pages, 3 figure

Flows of Knowledge from Universities and Federal Labs: Modeling the Flowof Patent Citations Over Time and Across Institutional and Geographic Boundari

The extent to which new technological knowledge flows across institutional and national boundaries is a question of great importance for public policy and the modeling of economic growth. This paper develops a model of the process generating subsequent citations to patents as a lens for viewing knowledge diffusion. We find that the probability of patent citation over time after a patent is granted fits well to a double-exponential function that can be interpreted as the mixture of diffusion and obsolescence functions. The results indicate that diffusion is geographically localized. Controlling for other factors, within-country citations are more numerous and come more quickly than those that cross country boundaries.

Potential surfaces for O atom-polymer reactions

Ab initio quantum chemistry methods are used to study the energetics of interactions of O atoms with organic compounds. Polyethylene (CH2)n has been chosen as the model system to study the interactions of O(3P) and O(1D) atoms with polymers. In particular, H abstraction is investigated and polyethylene is represented by a C3 (propane) oligomeric model. The gradient method, as implemented in the GRADSCF package of programs, is used to determine the geometries and energies of products and reactants. The saddle point, barrier geometry is determined by minimizing the squares of the gradients of the potential with respect to the internal coordinates. To correctly describe the change in bonding during the reaction at least a two configuration MCSCF (multiconfiguration self consistent field) or GVB (generalized valence bond) wave function has to be used. Basis sets include standard Pople and Dunning sets, however, increased with polarization functions and diffuse p functions on both the C and O atoms. The latter is important due to the O(-) character of the wave function at the saddle point and products. Normal modes and vibrational energy levels are given for the reactants, saddle points and products. Finally, quantitative energetics are obtained by implementing a small CAS (complete active space) approach followed by limited configuration interaction (CI) calculations. Comparisons are made with available experimental data

Patent Citations and International Knowledge Flow: The Cases of Korea and Taiwan

This paper examines patterns of knowledge diffusion from US and Japan to Korea and Taiwan using patent citations as an indicator of knowledge flow. We estimate a knowledge diffusion model using a data set of all patents granted in the U.S. to inventors residing in these four countries. Explicitly modeling the roles of technology proximity and knowledge decay and knowledge diffusion over time, we have found that knowledge diffusion from US and Japan to Korea and Taiwan exhibits quite different patterns. It is much more likely for Korean patents to cite Japanese patents than US patents, whereas Taiwanese inventors tend to learn evenly from both US and Japanese inventors. The frequency of a Korean patent citing a Japanese patent is almost twice that of the frequency of a Taiwanese patent citing a Japanese patent. We also find that a patent is much more likely to cite a patent from its own technological field than from another field.