International real business cycles : a re-visit

It is well known that several quantitative properties of international real business cycle models with are at odds with the data. First, the cross-country correlations are much higher for consumption than for output, while in the data the opposite is true (the BKK puzzle). Second, cross-country correlations of employment and investment are negative, while in the data they are positive. This paper quantitatively shows that preferences with a zero income effect on labor supply help generate a correct cross-country correlation in employment even without any restrictions on financial markets. In a bond economy, a zero income effect in labor supply, combined with time-to-build investment, can generate a positive cross-country correlation in investment, and the BKK puzzle is also resolved when the inter-temporal elasticity of substitution in labor supply is low.

Effects of taper length on traffic operations in construction zones.

Federal Highway Administration, Office of Research, Washington, D.C.

ASSESSMENT OF ENERGY CONSUMPTION IN GREENHOUSE PRODUCTION IN THE WEST REGION OF PORTUGAL

Greenhouse production is a very important activity in the West region of Portugal, with an area of approximately 800 ha where the regular production consists in two crops per year, one in winter-spring and the other in summer-autumn. Many growers are now prepared to better exploit market opportunities, since they know that the big export window opportunity is from June to September, when the production is difficult in other regions of south due to high temperatures. Grower’s use new and more productive varieties, either in soil or hydroponic systems, mostly in unheated greenhouses, naturally ventilated, and equipped with modern fertigation systems. Greenhouse production causes some environmental impacts due to the high use of inputs. Several improvements in technologies and crop practices may contribute to increase the use efficiency of resources, decreasing the negative environmental impacts. Greenhouse vegetable production in Northern EU countries is based on the supply of heating and differs significantly from the production system in the Southern EU countries. In the Northern countries, direct energy inputs, mostly for heating, are predominant while in the South the indirect energy input is also important, mainly associated with fertilizers, plastic cover materials and other auxiliary materials. The main objective of this work was to characterise the greenhouse production systems in the West region of Portugal, in order to evaluate the energetic consumptions (direct and indirect), the GHH emissions, the production costs and the farmer’s income. With this work the mostly important inputs were identified, allowing proposing alternative measures to improve efficiency and sustainability. All the data was obtained by surveys performed directly with growers, previously selected to be representative of the crop practices and greenhouse type of the region. However, more research should be performed in order to develop and to test technologies capable to improve resources use efficiency in greenhouse production.