The development of a system of European regional purchasing power parities

This paper discusses ways in which a system of Purchasing Power Parities defined at the NUTS-2 regional disaggregation could be developed, and what the implications could be for EU policy, particularly the evaluation of Structural Funds and the conclusions made thus far about regional convergence and development. Currently regional GDP in current prices is deflated using national purchasing power indices, mostly only derived from surveys undertaken in the capital cities of the Member States. For some Member States, the national PPP are corrected for price differences within the country, using spatial correction factors for individual price surveys, given these factors are provided by the countries. Clearly, therefore, for the majority of the countries, these estimates of regional GDP do not take any account of significant differences in cost of living within countries. This paper draws on the preliminary results of a research project being undertaken for Eurostat to examine options for deriving a system of regional prices. Much research has already been published at the level of international prices, partly through the International Comparison Programme (ICP), but little work has been carried out on inter-regional differences. The paper reviews briefly the theoretical and empirical literature on national PPPs. It then discusses key conceptual issues, including the problem of the difference between expenditure-based measures (used for national PPPs) versus the output-based procedure used to estimate regional GDP. A review of what data currently exists to inform estimates, particularly the detailed tables of consumer price indices (CPI), is followed by proposals for how a system of regional PPPs might be developed. This paper concludes with an examination of the potential implications of the work, how it could affect regional policy in the future and conclusions already made about regional development. Some stylised examples are used to show how adopting regional versus national prices could affect the results.

Oldest Varroa tolerant honey bee population provides insight into the origins of the global decline of honey bees

The ecto-parasitic mite Varroa destructor has transformed the previously inconsequential Deformed Wing Virus (DWV) into the most important honey bee viral pathogen responsible for the death of millions of colonies worldwide. Naturally, DWV persists as a low level covert infection transmitted between nest-mates. It has long been speculated that Varroa via immunosuppression of the bees, activate a covert infection into an overt one. Here we show that despite Varroa feeding on a population of 20-40 colonies for over 30 years on the remote island of Fernando de Noronha, Brazil no such activation has occurred and DWV loads have remained at borderline levels of detection. This supports the alternative theory that for a new vector borne viral transmission cycle to start, an outbreak of an overt infection must first occur within the host. Therefore, we predict that this honey bee population is a ticking time-bomb, protected by its isolated position and small population size. This unique association between mite and bee persists due to the evolution of low Varroa reproduction rates. So the population is not adapted to tolerate Varroa and DWV, rather the viral quasi-species has simply not yet evolved the necessary mutations to produce a virulent variant

Varroa destructor reproduction and cell re-capping in mite-resistant Apis mellifera populations

Globalization has facilitated the spread of emerging pests such as the Varroa destructor mite, resulting in the near global distribution of the pest. In South African and Brazilian honey bees, mite-resistant colonies appeared within a decade; in Europe, mite-resistant colonies are rare, but several of these exhibited high levels of “re-capping” behavior. We studied re-capping in Varroa-naïve (UK/Australia) and Varroa-resistant (South Africa and Brazil) populations and found very low and very high levels, respectively, with the resistant populations targeting mite-infested cells. Furthermore, 54% of artificially infested A. m. capensis worker cells were removed after 10 days and 83% of the remaining infested cells were re-capped. Such targeted re-capping of drone cells did not occur. We propose that cell opening is a fundamental trait in mite-resistant populations and that re-capping is an accurate proxy for this behavior

Computing excluded minors for classes of matroids representable over partial fields

We describe an implementation of a computer search for the "small" excluded minors for a class of matroids representable over a partial field. Using these techniques, we enumerate the excluded minors on at most 15 elements for both the class of dyadic matroids, and the class of 2-regular matroids. We conjecture that there are no other excluded minors for the class of 2-regular matroids; whereas, on the other hand, we show that there is a 16-element excluded minor for the class of dyadic matroids.We describe an implementation of a computer search for the "small" excluded minors for a class of matroids representable over a partial field. Using these techniques, we enumerate the excluded minors on at most 15 elements for both the class of dyadic matroids, and the class of 2-regular matroids. We conjecture that there are no other excluded minors for the class of 2-regular matroids; whereas, on the other hand, we show that there is a 16-element excluded minor for the class of dyadic matroids