Exploratory bottom trawling in Lake Victoria

When the Lake Victoria Fisheries Research Project began, the background information necessary for the successful application of quantitative stock assessment was lacking. For this. reason and also due to the size of Lake Victoria, the complexity and variety of its many habitats, and its multispecies fishery, it was decided that initial stock assessment studies should consist of a lake wide survey using a variety of exploratory fishing methods

Patterns of dominant flows in the world trade web

The large-scale organization of the world economies is exhibiting increasingly levels of local heterogeneity and global interdependency. Understanding the relation between local and global features calls for analytical tools able to uncover the global emerging organization of the international trade network. Here we analyze the world network of bilateral trade imbalances and characterize its overall flux organization, unraveling local and global high-flux pathways that define the backbone of the trade system. We develop a general procedure capable to progressively filter out in a consistent and quantitative way the dominant trade channels. This procedure is completely general and can be applied to any weighted network to detect the underlying structure of transport flows. The trade fluxes properties of the world trade web determines a ranking of trade partnerships that highlights global interdependencies, providing information not accessible by simple local analysis. The present work provides new quantitative tools for a dynamical approach to the propagation of economic crises

Relativistic nature of a magnetoelectric modulus of Cr_2O_3-crystals: a new 4-dimensional pseudoscalar and its measurement

Earlier, the magnetoelectric effect of chromium sesquioxide Cr_2O_3 has been determined experimentally as a function of temperature. One measures the electric field-induced magnetization on Cr_2O_3 crystals or the magnetic field-induced polarization. From the magnetoelectric moduli of Cr_2O_3 we extract a 4-dimensional relativistic invariant pseudoscalar $\widetilde{\alpha}$. It is temperature dependent and of the order of 10^{-4}/Z_0, with Z_0 as vacuum impedance. We show that the new pseudoscalar is odd under parity transformation and odd under time inversion. Moreover, $\widetilde{\alpha}$ is for Cr_2O_3 what Tellegen's gyrator is for two port theory, the axion field for axion electrodynamics, and the PEMC (perfect electromagnetic conductor) for electrical engineering.Comment: Revtex, 36 pages, 9 figures (submitted in low resolution, better quality figures are available from the authors

Bureau of Networks and Observations

Role of the Bureau: To advocate and encourage implementation of the Core and Co-location Network to satisfy GGOS requirements, to monitor the status of the network and project its future condition, and to support and advocate for infrastructure critical for the development of data products essential to GGOS

Measuring the Effect of Revealed Cultural Preferences on Tourism Exports

The aim of this article is to propose a novel method for measuring the effect of cultural preference on bilateral tourism receipts. The method applied is inspired from Disdier et al. (2010). Using the UNESCO classification and data on bilateral trade in cultural product, a proxy for cultural preferences is constructed. The variable is used in a gravity model for tourism export, which is estimated using a two-step procedure to avoid issues related to endogeneity. The data set used is a panel of 12 OECD countries for a period of 11 years. The variable for cultural preferences eliminates the problems with traditional methods, which by using dummy variables to account for cultural preferences, assume that the latter are time-invariant and symmetrical. The cultural variable constructed is found to be significant in explaining bilateral tourism exports with an elasticity of 0.39. © The Author(s) 2018