N II 5668-5712, a New Class of Spectral Features in Eta Carinae

We report on the N II 5668-5712 emission and absorption lines in the spectrum of Eta Carinae. Spectral lines of the stellar wind regions can be classified into four physically distinct categories: 1) low-excitation emission such as H I and Fe II, 2) higher excitation He I features, 3) the N II lines discussed in this paper, and 4) He II emission. These categories have different combinations of radial velocity behavior, excitation processes, and dependences on the secondary star. The N II lines are the only known features that originate in "normal" undisturbed zones of the primary wind but depend primarily on the location of the hot secondary star. N II probably excludes some proposed models, such as those where He I lines originate in the secondary star's wind or in an accretion disk.Comment: 4 figures, 1 tabl

DGD Gallery: Storage, sharing, and publication of digital research data

We describe a project, called the "Discretization in Geometry and Dynamics Gallery", or DGD Gallery for short, whose goal is to store geometric data and to make it publicly available. The DGD Gallery offers an online web service for the storage, sharing, and publication of digital research data.Comment: 19 pages, 8 figures, to appear in "Advances in Discrete Differential Geometry", ed. A. I. Bobenko, Springer, 201

Secular Changes in Eta Carinae's Wind 1998-2011

Stellar wind-emission features in the spectrum of eta Carinae have decreased by factors of 1.5-3 relative to the continuum within the last 10 years. We investigate a large data set from several instruments (STIS, GMOS, UVES) obtained between 1998 and 2011 and we analyze the progression of spectral changes in the direct view of the star, in the reflected polar-on spectra at FOS4, and at the Weigelt knots. We find that the spectral changes occurred gradually on a time scale of about 10 years and that they are dependent on the viewing angle. The line strengths declined most in our direct view of the star. About a decade ago, broad stellar wind-emission features were much stronger in our line-of-sight view of the star than at FOS4. After the 2009 event, the wind-emission line strengths are now very similar at both locations. High-excitation He I and N II absorption lines in direct view of the star strengthened gradually. The terminal velocity of Balmer P Cyg absorption lines now appears to be less latitude-dependent and the absorption strength may have weakened at FOS4. Latitude-dependent alterations in the mass-loss rate and the ionization structure of eta Carinae's wind are likely explanations for the observed spectral changes.Comment: 42 pages, 12 figures, 2 table

Agency practically imparted: a media-didactical workshop conception

Im folgenden Artikel wird ein mehrstufiges mediendidaktisches Workshop-Konzept vorstellt. Ziel des Angebots ist die praxisnahe Vermittlung von Grundlagen anhand von Fallbeispielen. Der Workshop wurde im Rahmen des seit 2012 durch das BMBF geförderten, sächsischen Verbundprojekts Lehrpraxis im Transfer (LiT) zur Qualifizierung für den Bereich Neue Medien entwickelt. Im Artikel werden die Philosophie und Genese von «Neue Lehre durch Neue Medien? – Sinnvoller Einsatz von Neuen Medien in der Hochschullehre» dargestellt und ein Einblick in Konzeption und Durchführung der Weiterbildung gegeben. Das Konzept richtet sich an Vertreter/innen aller Fachrichtungen und vermittelt mediendidaktische und damit einhergehend hochschuldidaktische Grundlagen. Zur niedrigschwelligen Veranschaulichung der Thematik wird mit Beispielen guter Lehrpraxis gearbeitet. Das Angebot richtet sich an Lehrende, die das Sächsische Hochschuldidaktik Zertifikat erlangen wollen und ist im Zertifikatsprogramm des Hochschuldidaktischen Zentrums Sachsen (HDS) im Bereich «Neue Medien» anrechenbar. Derzeit wird «Neue Lehre durch Neue Medien?» als offene Bildungsressource aufbereitet und zur Nutzung für Weiterbildner/innen zur Verfügung gestellt.The following article introduces a multilevel media-didactical workshop conception, which was developed within the Saxonian network-project for Higher Education Lehrpraxis im Transfer. The aim is the practical teaching of basic didactics through case studies. The workshop was developed within the Saxonian network-project Lehrpraxis im Transfer (LiT) in the field of new media. The article will present the philosophy and generation of «Neue Lehre durch Neue Medien? – Sinnvoller Einsatz von Neuen Medien in der Hochschullehre» and pursue the conception and its implementation. It focuses all teachers in higher education of all subjects and introduces basics in media-didactics and Higher Education by the use of good practice. The workshop addresses teachers in Higher Education, aiming to achieve the certificate of the Hochschuldidaktisches Zentrum Sachsen – Center for Higher Education in Saxony (HDS) within the field of new media. «Neue Lehre durch Neue Medien?» is currently edited for the use as Open Educational Resource

Track, then Decide: Category-Agnostic Vision-based Multi-Object Tracking

The most common paradigm for vision-based multi-object tracking is tracking-by-detection, due to the availability of reliable detectors for several important object categories such as cars and pedestrians. However, future mobile systems will need a capability to cope with rich human-made environments, in which obtaining detectors for every possible object category would be infeasible. In this paper, we propose a model-free multi-object tracking approach that uses a category-agnostic image segmentation method to track objects. We present an efficient segmentation mask-based tracker which associates pixel-precise masks reported by the segmentation. Our approach can utilize semantic information whenever it is available for classifying objects at the track level, while retaining the capability to track generic unknown objects in the absence of such information. We demonstrate experimentally that our approach achieves performance comparable to state-of-the-art tracking-by-detection methods for popular object categories such as cars and pedestrians. Additionally, we show that the proposed method can discover and robustly track a large variety of other objects.Comment: ICRA'18 submissio

Metal-Insulator Transition in a Generalized Hubbard Model with Correlated Hopping at Half-Filling

In the present paper metal-insulator transition is studied in a generalized Hubbard model with correlated hopping at half-filling and zero temperature. Single-particle Green function and energy spectrum of electron system are calculated. The expressions for energy gap width and the concentration of polar states (holes or doublons) are obtained. The conditions for metallic and insulating states are found.Comment: 11 pages, 2 eps figures, Latex 2.09, submitted to Phys. Stat. Sol. (B

Universal flow-density relation of single-file bicycle, pedestrian and car motion

The relation between flow and density is an essential quantitative characteristic to describe the efficiency of traffic systems. We have performed experiments with single-file motion of bicycles and compare the results with previous studies for car and pedestrian motion in similar setups. In the space-time diagrams we observe three different states of motion (free flow state, jammed state and stop-and-go waves) in all these systems. Despite of their obvious differences they are described by a universal fundamental diagram after proper rescaling of space and time which takes into account the size and free velocity of the three kinds of agents. This indicates that the similarities between the systems go deeper than expected.Comment: 5 pages, 5 figure