Effects of Geometrical Discontinuities on Distributed Passive Intermodulation in Printed Lines

This paper presents the results of experimental study of passive intermodulation (PIM) generation in microstrip lines with U-shaped and meandered strips, impedance tapers, and strips with the profiled edges. It is shown that the geometrical discontinuities in printed circuits may have a noticeable impact on distributed PIM generation even when their effect is indiscernible in the linear regime measurements. A consistent interpretation of the observed phenomena has been proposed on the basis of the phase synchronism in the four-wave mixing process. The results of this study reveal new features of PIM production important for the design and characterization of low-PIM microstrip circuits. © 2010 IEEE.

Migration, human capital accumulation and economic development

We study how the possibility of migration changes the composition of human capital in sending countries, and how this affects development. In our model, growth is driven by productivity growth, which occurs via imitation or innovation. Both activities use the same types of skilled labour as input, albeit with different intensities. Heterogenous agents accumulate skills in response to economic incentives. Migration distorts these incentives, and the accumulation of human capital. This slows down, or even hinders, economic development. The effect is stronger, the farther away the country is from the technological frontier. (C) 2008 Elsevier B.V. All rights reserved.