Tuning the localized surface plasmon resonance in copper chalcogenide nanoparticles

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The Wolf-Rayet stars in M31: I. Analysis of the late-type WN stars

Context: Comprehensive studies of Wolf-Rayet stars were performed in the past for the Galactic and the LMC population. The results revealed significant differences, but also unexpected similarities between the WR populations of these different galaxies. Analyzing the WR stars in M31 will extend our understanding of these objects in different galactic environments. Aims: The present study aims at the late-type WN stars in M31. The stellar and wind parameters will tell about the formation of WR stars in other galaxies with different metallicity and star formation histories. The obtained parameters will provide constraints to the evolution of massive stars in the environment of M31. Methods: We used the latest version of the Potsdam Wolf-Rayet model atmosphere code to analyze the stars via fitting optical spectra and photometric data. To account for the relatively low temperatures of the late WN10 and WN11 subtypes, our WN models have been extended into this temperature regime. Results: Stellar and atmospheric parameters are derived for all known late-type WN stars in M31 with available spectra. All of these stars still have hydrogen in their outer envelopes, some of them up to 50% by mass. The stars are located on the cool side of the zero age main sequence in the Hertzsprung-Russell diagram, while their luminosities range from $10^5$ to $10^6$ Lsun. It is remarkable that no star exceeds $10^6$ Lsun. Conclusions: If formed via single-star evolution, the late-type WN stars in M31 stem from an initial mass range between 20 and 60 Msun. From the very late-type WN9-11 stars, only one star is located in the S Doradus instability strip. We do not find any late-type WN stars with the high luminosities known in the Milky Way.Comment: 11+11 pages, 13+18 figures, A&A, in pres

Selbstgerechtigkeit – Selbstermächtigte Status-Degradierungszeremonien von Online-Petitionen bis zum Lynchen 2.0

An increasing lack of commitment and brutalization was observed due to the erosion of traditional communities in late modernism (cf. Duerr 1993; Sennet 1998). In Social Media, this is shown as an aggressive style (flaming) or as "hate speech" (cf. Butler 2013), increasingly in organized forms of ensembles of actors of aggression directed specifically against individuals. This libel and these hate acts underlie a complex practice which can be described with Harold Garfinkel's concept as "status degradation ceremony". Garfinkel's terms refer to court cases, i. e. an institutionalized form of aggression exercising – according to Sigmund Freud's terms one of the main benefits of every culture in order to prevent violent squalor and brutality. At the same time, however, Freud also expressed unease ("Unbehagen") that this aggression could more or less break with institutional failure. Today, such processes can be increasingly observed in a bandwidth ranging from simple online petitions to radical forms of vigilantism. In order to understand why individuals take the law into their own hands and – often associated with a more or less large swarm formation – why they are trying to define law, to judge, and even to execute their own "judgments" outside of the democratically constituted legal system, a second concept is introduced, the concept of "Selbstermächtigung" which refers to practices of autonomy. This concept of "Selbstermächtigung" is understood as a time diagnostic term to describe a number of communicative practices which could jeopardize democracy in one of its institutional foundations in question: its legal constitution. "Selbstermächtigung" describes a contemporary mentality which contains a strong, emotionally charged tension between the individual and the institution namely in all sorts of social institutions, such as in health, science, but also democracy – which only just enables these criticism of institutions. From the two analytical concepts of "Selbstermächtigung" and the status degradation ceremony, we can develop the concept of a "self-authorized status degradation ceremony". With this concept, we can examine both simple online petitions and extreme forms of vigilante justice, which are similar to lynching. This is done plausible on the basis of exemplary analyzes. Finally, the danger is clear that the anti institutionally polarized mentality of "Selbstermächtigung" exactly threatens the institution that enables them