Separation and Renaming in Nominal Sets

Nominal sets provide a foundation for reasoning about names. They are used primarily in syntax with binders, but also, e.g., to model automata over infinite alphabets. In this paper, nominal sets are related to nominal renaming sets, which involve arbitrary substitutions rather than permutations, through a categorical adjunction. In particular, the left adjoint relates the separated product of nominal sets to the Cartesian product of nominal renaming sets. Based on these results, we define the new notion of separated nominal automata. We show that these automata can be exponentially smaller than classical nominal automata, if the semantics is closed under substitutions

Diversification in euro area stock markets: country versus industry

The harmonisation of fiscal and economic policy within the European Monetary Union (EMU) has had a considerable impact on the economies of member countries in the past decade. In particular, several studies indicate that the proceeding economic integration among euro area countries has important consequences for the factors driving asset returns in financial markets. This study concentrates on the implications of the changing structure of security returns for asset management. Using recent euro area stock markets data, we find clear evidence that diversification over industries yields more efficient portfolios than diversification over countries. We show that this result is robust with respect to the information technology-hype and different volatility regimes. This contrasts with e.g. Rouwenhorst (1999), who finds, based on a different methodology and a different sample period, that country diversification strategies are superior. We regard this paper as a robustness check challenging the existing strand of literature and show that Rouwenhorst’s (1999) conclusions seem to be outdated. JEL Classification: G11, G15country, EMU, euro area stock markets, industry factors, portfolio diversification

Introduction of ramp-type technology in HTS quasiparticle injection devices

Injection of quasiparticles with an energy larger than the superconducting gap into a superconducting strip results in breaking of Cooper-pairs and hence the suppression of the superconducting properties. Experiments using planar injection devices made of HTS materials with various barrier materials showed current gains varying from 2 up to 15 at 77 K. By changing the junction size and therefore the superconducting volume the current gain could be increased. A further reduction of the junction volume is very difficult using the planar device geometry. However, by applying the ramp-type technology it is possible to reduce the junction volume by at least one order of magnitude and a further increase in current gain is expected. Another advantage of this technology is the formation of in-situ barriers and electrodes and hence a better control of the junction characteristics should be possible, also the compatibility with the processes involved making RSFQ devices can be interesting for later applications. We have fabricated ramp-type injection devices, using various types of barriers. Characterization of these devices has been performed and the results of these experiments will be presented and discussed