This paper introduces endogenous product entry and exit based on creation and destruction of product variety in a general equilibrium model. Recessionary technology shocks induce exit of unprofitable products on impact, allocating resources towards more productive production lines. However, during the recovery phase, less productive production lines survive destruction, counteracting the original increase in productivity. The analysis shows that recoveries hinge on lower product destruction rather than higher product creation. We find that product heterogeneity and the persistence of technology shocks play a critical role for the cyclicality of product turnover. Endogenous product destruction is important to evaluate the effect of permanent policies of entry deregulation and subsidies aimed to stimulate the economy.

JEL classification: F12 F41 F43 Keywords:Real exchange rate Home biased equity puzzle Firm entry Firm heterogeneity This paper analyzes equity and bond positions in a two-country Dynamic Stochastic General Equilibrium model where the number of varieties, i.e., the extensive margins of products available to consumers, is endogenously determined. Fluctuations in the welfare-based real exchange rate, including those in the number of varieties, matter to international consumption risk sharing. We investigate the implication of such "variety risk" for the optimal portfolio choice and show that the variety risk generates home-biased equity positions, strengthening those obtained with the standard model in the literature. We also find preliminary empirical support for the mechanism.

Experimental results are presented for film cooling effectiveness with injection from both a single row and multiple rows of holes with spanwise hole-to-hole spacings of three hole diameters. In the multi-row cases, the injection holes were arranged in staggered patterns with streamwise row-to-row spacings of five or ten hole diameters. Adiabatic wall temperature distributions near and downstream of injection holes were well visualized using a scanning infrared camera. The effect of mainstream pressure gradient was partially included. The additive nature of multi-row film cooling was demonstrated experimentally, in agreement with the Sellers superposition model.

We study the effect of natural disasters on port-level exports. We model the interaction between firms and ports to study how strongly exports from one port are affected by changes in the cost of exporting at neighboring ports. We extend the standard trade model with heterogeneous firms to a multiple port structure where exporting is subject to port specific local transportation costs, port specific fixed export costs and international bilateral trade costs. We show that gravity distortion due to firm heterogeneity is conditional on the comparative advantage at the port level and resulting substitution of exports across ports. We present evidence of the substitution effect using the 2011 Great East Japan Earthquake, indicating that at least 40% of exports was substituted to other ports following the disaster. The substitution effect is the strongest in technology intensive product categories, which suggests an interaction between supply chains and domestic trade costs.