Consumer Learning and Hybrid Vehicle Adoption

We study the diffusion of hybrid vehicles among consumers. Using data on sales of 11 different models over seven years, we identify the effect of the penetration rate--total cumulative hybrid sales per capita--on new hybrid purchases. The penetration rate significantly affects new purchases, and the effect differs by hybrid model. In particular, we find a positive diffusion effect from the Toyota Prius and a negative diffusion effect from the Honda Insight, with elasticities of 0.23 to 0.85 for the Prius and -0.08 to -0.32 for the Insight. This finding is consistent with our model of model-specific learning along with anecdotal evidence that early Insight models were perceived to be of lower quality than Prius models. Higher Insight penetration rates gave a negative signal about hybrid quality and inhibited rather than promoted hybrid adoption. The findings are relevant for policy designed to promote new technologies.

Curvature Diffusions in General Relativity

We define and study on Lorentz manifolds a family of covariant diffusions in which the quadratic variation is locally determined by the curvature. This allows the interpretation of the diffusion effect on a particle by its interaction with the ambient space-time. We will focus on the case of warped products, especially Robertson-Walker manifolds, and analyse their asymptotic behaviour in the case of Einstein-de Sitter-like manifolds.Comment: 34 page

Information Diffusion Effects in Individual Investors' Common Stock Purchases: Covet Thy Neighbors' Investment Choices

Using data on stock purchases individual investors made through a discount broker from 1991 to 1996, we study information diffusion effects the relation between household investment choices and those made by their neighbors. A ten percentage point increase in neighbors' purchases of stocks from an industry is associated with a two percentage point increase in the household's own purchases of stocks from that industry, with the effect considerably larger for purchases of local stocks. The presence of information diffusion effects is robust to controls for potential inside information effects and to household fixed effects. Upon controlling for aggregate trading patterns, households' and neighbors' investment style preferences, and the industry composition of local firms, we attribute approximately one-third to one-half of the overall diffusion effect to word-of-mouth communication. Disentangling the overall diffusion effect suggests that the significant relation between our measures of information diffusion and subsequent industry-level returns appears to be driven by its word-of-mouth component.

Two-dimensional model of intrinsic magnetic flux losses in helical flux compression generators

Helical Flux Compression Generators (HFCG) are used for generation of mega-amper current and high magnetic fields. We propose the two dimensional HFCG filament model based on the new description of the stator and armature contact point. The model developed enables one to quantitatively describe the intrinsic magnetic flux losses and predict the results of experiments with various types of HFCGs. We present the effective resistance calculations based on the non-linear magnetic diffusion effect describing HFCG performance under the strong conductor heating by currents.Comment: 29 pages,18 figure