Revisiting the Sectoral Linder Hypothesis: Aggregation Bias or Fixed Costs?

This paper reassesses and revisits the Sectoral Linder Hypothesis due to Hallak (2010), according to which similar tastes for quality lead to more intensive trade between similar countries. First, it will be shown that allowing for strictly non-homothetic preferences reduces confoundedness and improves results. Moreover, the country/firm level extensive margin is taken into account. This approach allows controlling for unobserved firm level heterogeneity and selection bias (Helpman et al. 2008). The advantage in terms of interpretation is that differences in coefficients at the two margins can be linked to fixed cost effects. The attempt is to show that the Linder effect is confounded with fixed (opportunity) costs of trade thereby leading to downward biased results. There is some evidence that this effect is exacerbated at the aggregate, intersectoral level. Fixed (opportunity) costs seem to be higher in sectors where similar countries trade a lot. The evidence reinforces the sectoral Linder hypothesis, and suggests that the patterns might prevail at the more aggregate levels. Other robustness checks suggest that results are not confined to products that are vertically differentiated

Special studies of AROD system concepts and designs

Signal to noise ratios in airborne range and orbit determination system, and carrier and range loop performance analyse

The development of a solar powered residential heating and cooling system

A solar energy collector design is disclosed that would be efficient for both energy transfer and fluid flow, based upon extensive parametric analyses. Thermal design requirements are generated for the energy storage systems which utilizes sensible heat storage in water. Properly size system components (including the collector and storage) and a practical, efficient total system configuration are determined by means of computer simulation of system performance

Nonlinear competition between asters and stripes in filament-motor-systems

A model for polar filaments interacting via molecular motor complexes is investigated which exhibits bifurcations to spatial patterns. It is shown that the homogeneous distribution of filaments, such as actin or microtubules, may become either unstable with respect to an orientational instability of a finite wave number or with respect to modulations of the filament density, where long wavelength modes are amplified as well. Above threshold nonlinear interactions select either stripe patterns or periodic asters. The existence and stability ranges of each pattern close to threshold are predicted in terms of a weakly nonlinear perturbation analysis, which is confirmed by numerical simulations of the basic model equations. The two relevant parameters determining the bifurcation scenario of the model can be related to the concentrations of the active molecular motors and of the filaments respectively, which both could be easily regulated by the cell.Comment: 13 pages, 7 figure