Topology of the World Trade Web

Economy, and consequently trade, is a fundamental part of human social organization which, until now, has not been studied within the network modelling framework. Networks are mathematical tools used in the modelling of a wide variety of systems in social and natural science. Examples of these networks range from metabolic and cell networks to technological webs. Here we present the first empirical characterization of the world trade web, that is, the network built upon the trade relationships between different countries in the world. This network displays the typical properties of complex networks, namely, scale-free degree distribution, the {\it small world} property, a high clustering coefficient and, in addition, degree-degree correlation between different vertices. All these properties make the world trade web a complex network, which is far from being well-described through a classical random network description

The Real Effects of the Euro: Evidence from Corporate Investments

We study how the adoption of the euro as the common currency in Europe has affected firms' investment rates. Using corporate data from the eleven countries that adopted the euro in January 1999, as well as from a control sample of five other European countries, our paper shows that: (i) the euro has increased investments for firms from countries that previously had weak currencies, (ii) the euro has had a positive impact on financially constrained firms' investments, and (iii) the euro has decreased investments for financially unconstrained firms from countries that previously had strong currencies. Copyright 2006, Oxford University Press.

Role of soil rhizobacteria in phytoremediation of heavy metal contaminated soils

Heavy metal pollution of soil is a significant environmental problem and has its negative impact on human health and agriculture. Rhizosphere, as an important interface of soil and plant, plays a significant role in phytoremediation of contaminated soil by heavy metals, in which, microbial populations are known to affect heavy metal mobility and availability to the plant through release of chelating agents, acidification, phosphate solubilization and redox changes, and therefore, have potential to enhance phytoremediation processes. Phytoremediation strategies with appropriate heavy metal-adapted rhizobacteria have received more and more attention. This article paper reviews some recent advances in effect and significance of rhizobacteria in phytoremediation of heavy metal contaminated soils. There is also a need to improve our understanding of the mechanisms involved in the transfer and mobilization of heavy metals by rhizobacteria and to conduct research on the selection of microbial isolates from rhizosphere of plants growing on heavy metal contaminated soils for specific restoration programmes