Spectropolarimetry with the DAO 1.8-m telescope

The fast-switching DAO spectropolarimeter mounted on the 1.8-m Plaskett telescope started operation in 2007. Almost 14,000 medium-resolution (R=15,000) polarimetric spectra of 65 O - F type stars have been obtained since then in the course of three ongoing projects: the DAO Magnetic Field Survey, supporting observations for the CFHT MiMeS survey, and an investigation of the systematic differences between the observed longitudinal field measured with the Hbeta line and metallic lines. The projects are briefly described here. The current status as well as some results are presented.Comment: "Magnetic Stars", Proceedings of the International Conference, Nizhny Arkhyz, 27 August - 1 September 201

Degeneracy between Abelian and Non-Abelian Strings

In a model that supports both Abelian (Abrikosov-Nielsen-Olesen) and non-Abelian strings we analyze the parameter space to find examples in which these strings not only coexist but are degenerate in tension. We prove that both solutions are locally stable, i.e there are no negative modes in the string background. The tension degeneracy is achieved at the classical level and is expected to be lifted by quantum corrections. The set up of the model, analogous to that of Witten's superconducting cosmic strings, had been extended to include non-Abelian strings

The weakness of the pigeonhole principle under hyperarithmetical reductions

The infinite pigeonhole principle for 2-partitions ($\mathsf{RT}^1_2$) asserts the existence, for every set $A$, of an infinite subset of $A$ or of its complement. In this paper, we study the infinite pigeonhole principle from a computability-theoretic viewpoint. We prove in particular that $\mathsf{RT}^1_2$ admits strong cone avoidance for arithmetical and hyperarithmetical reductions. We also prove the existence, for every $\Delta^0_n$ set, of an infinite low${}_n$ subset of it or its complement. This answers a question of Wang. For this, we design a new notion of forcing which generalizes the first and second-jump control of Cholak, Jockusch and Slaman.Comment: 29 page

Comedy, pain and nonsense at the Red Moon Cafe: The Little Tramp's death by service work in Modern Times

Paper presented at the Art of Management Conference, 2004, ParisThis paper was originally presented at the Art of Management Conference, in Paris in 2004. The paper is an essay about The Red Moon Cafe scene in Charlie Chaplin's masterpeiece, Modern Times (1936). In this scene, famous for the Nonsense Song, where the Little Tramp 'speaks' for the first and the last time on screen, Chaplin explores service work, especially the theme of authenticity, and uses his skills as a dancer, musician, choreographer, and film maker, to provide a commentary on service work