Rotation of the solar convection zone from helioseismology

Helioseismology has provided very detailed inferences about rotation of the solar interior. Within the convection zone the rotation rate roughly shares the latitudinal variation seen in the surface differential rotation. The transition to the nearly uniformly rotating radiative interior takes place in a narrow tachocline, which is likely important to the operation of the solar magnetic cycle.The convection-zone rotation displays zonal flows, regions of slightly more rapid and slow rotation, extending over much of the depth of the convection zone and converging towards the equator as the solar cycle progresses. In addition, there is some evidence for a quasi-periodic variation in rotation, with a period of around 1.3 yr, at the equator near the bottom of the convection zone.Comment: 12 pages, 8 figures. To appear in Proc. IAU Symposium 239: Convection in Astrophysics,eds F. Kupka, I. W. Roxburgh & K. L. Chan, Cambridge University Pres

Four steps in the history of museum technologies and visitors' digital participation

The hypothesis of this article is that the authentic and auratic exhibited objects in museums enter into a dialogue with surrounding paratexts. The paratexts anchor and change the meaning of the exhibited object in the museum context. Recent years have indicated a tendency for museum paratexts to grow increasingly allographic, i.e., visitors generate them both in situ and online as a part of Web 2.0 participation. The verification and documentation of this hypothesis are partly empirical, partly historical. The empirical research consists of an examination of the exhibition and display technologies used today in three different museums and galleries: the Bode Museum in Berlin, the Victoria and Albert Museum and Dr. Johnson's House in London.    The historical verification and documentation in this article describe four steps in the development of exhibition technologies: the Boydell Shakespeare Gallery (1789-1805), the post-photographic museum (the 1850s), audio guides, as well as a special focus on how museum paratexts have become independent today in its digital and participatory form. In this way, the article sketches the historical development of curating towards the digital and paratextual participation of visitors and audience. Here the argumentation is based on how the displayed object creates signification in its position between its autonomy and its contexts. The following display technologies are described and analysed: stipple engraving, photography, the audio guide, and the interactive, digital Anota pen and its Internet server.    In conclusion, the article asks where the place of signification or meaning of the exhibited object has moved to in the face of the increased degree of visitor participation. The tentative answer is that the signification generating process has moved away from the historical context of the object and towards the contemporary world of the visitor. The article connects this change in cultural discourse with Karin Sander's archaeological imagination and in a wider sense with the concept of negotiation from new historicism.The hypothesis of this article is that the authentic and auratic exhibited objects in museums enter into a dialogue with surrounding paratexts. The paratexts anchor and change the meaning of the exhibited object in the museum context. Recent years have indicated a tendency for museum paratexts to grow increasingly allographic, i.e., visitors generate them both in situ and online as a part of Web 2.0 participation. The verification and documentation of this hypothesis are partly empirical, partly historical. The empirical research consists of an examination of the exhibition and display technologies used today in three different museums and galleries: the Bode Museum in Berlin, the Victoria and Albert Museum and Dr. Johnson's House in London.    The historical verification and documentation in this article describe four steps in the development of exhibition technologies: the Boydell Shakespeare Gallery (1789-1805), the post-photographic museum (the 1850s), audio guides, as well as a special focus on how museum paratexts have become independent today in its digital and participatory form. In this way, the article sketches the historical development of curating towards the digital and paratextual participation of visitors and audience. Here the argumentation is based on how the displayed object creates signification in its position between its autonomy and its contexts. The following display technologies are described and analysed: stipple engraving, photography, the audio guide, and the interactive, digital Anota pen and its Internet server.    In conclusion, the article asks where the place of signification or meaning of the exhibited object has moved to in the face of the increased degree of visitor participation. The tentative answer is that the signification generating process has moved away from the historical context of the object and towards the contemporary world of the visitor. The article connects this change in cultural discourse with Karin Sander's archaeological imagination and in a wider sense with the concept of negotiation from new historicism