Wind-driving protostellar accretion discs. I. Formulation and parameter constraints

We study a model of weakly ionized, protostellar accretion discs that are threaded by a large-scale, ordered magnetic field and power a centrifugally driven wind. We consider the limiting case where the wind is the main repository of the excess disc angular momentum and generalize the radially localized disc model of Wardle & K\"onigl (1993), which focussed on the ambipolar diffusion regime, to other field diffusivity regimes, notably Hall and Ohm. We present a general formulation of the problem for nearly Keplerian, vertically isothermal discs using both the conductivity-tensor and the multi-fluid approaches and simplify it to a normalized system of ordinary differential equations in the vertical space coordinate. We determine the relevant parameters of the problem and investigate, using the vertical-hydrostatic-equilibrium approximation and other simplifications, the parameter constraints on physically viable solutions for discs in which the neutral particles are dynamically well coupled to the field already at the midplane. When the charged particles constitute a two-component ion--electron plasma one can identify four distinct sub-regimes in the parameter domain where the Hall diffusivity dominates and three sub-regimes in the Ohm-dominated domain. Two of the Hall sub-regimes can be characterized as being ambipolar diffusion-like and two as being Ohm-like. When the two-component plasma consists instead of positively and negatively charged grains of equal mass, the entire Hall domain and one of the Ohm sub-regimes disappear. In all viable solutions the midplane neutral--ion momentum exchange time is shorter than the local orbital time. Vertical magnetic squeezing always dominates over gravitational tidal compression in this model. (Abridged)Comment: 23 pages, 2 figures, 4 tables; accepted for publication in MNRA

Thales bis Diophant

Diese Arbeit präsentiert antike griechische Mathematiker und ihren Einfluss auf den Mathematikunterricht heute. Neben kurzen Darstellung des Lebens und der Philosophie der verschiedenen Mathematiker, wird auf ihre wichtigsten mathematischen Leistungen eingegangen. Das Hauptaugenmerk liegt dabei auf Errungenschaften, die für einen Schulunterricht relevant sind. Den Abschluss jedes Kapitels bildet eine Darstellung des Einflusses der antiken griechischen Mathematik auf den aktuellen Lehrplan und auf verschiedene Schulbücher

Die Kommerzialisierung des Kinderfernsehens unter besonderer Berücksichtigung des Merchandising

Die vorliegende Arbeit thematisiert die Kommerzialisierungsentwicklungen im Kinderfernsehprogramm im deutschsprachigen Raum unter besonderer Berücksichtigung der Praxis des Merchandising. Die Beobachtung, dass uns Figuren aus dem Kinderprogramm längst nicht mehr ausschließlich im Fernsehen allein begegnen, sondern in mannigfacher Form auch auf Alltagsgegenständen oder als Spielwaren, stellte dabei den Ausgangspunkt des Themeninteresses dar. Es galt aufzuzeigen, wie es überhaupt dazu kam, dass man mittlerweile von einem „Merchandising-Boom“ mit Themen des Kinder-TV sprechen kann. Als methodisches Vorgehen wurde dabei die Zusammenschau bestehender Forschungsergebnisse aus den Bereichen Kinderfernseh-Forschung, Medienökonomie und Medienpädagogik gewählt. Es stellte sich heraus, dass sich die hinter dem Merchandising stehenden Vertragsabwicklungen, die die Lizensierung von Inhalten, Personen, Figuren, etc. betreffen (Licensing), mittlerweile zu einem zentralen Faktor in der Finanzierung von Fernsehproduktionen entwickelt haben. Es liegt im Interesse der Fernsehanstalten, Lizenzprodukte zu ihren Sendungen auf dem Markt zu bringen, um die Aufmerksamkeit der Kinder zunächst auf das Programm und schließlich auch auf den Sender selbst zu lenken. Andererseits war zu erläutern, welche (gesellschaftlichen) Entwicklungen diesen Boom begünstig(t)en. Es ist unbestreitbar, dass Kindheit heutzutage gleichzeitig als eine Medienkindheit und darüber hinaus auch als eine Konsumkindheit verstanden werden muss. Die Mediatisierung der kindlichen Lebenswelt ist - wie anhand mehrerer Faktoren, darunter der Medienbesitz, dargestellt – weit fortgeschritten. Und auch die Kaufkraft der Kinder ist im Laufe der Zeit verstärkt in den Fokus der Wirtschaft getreten, die in Gemeinschaft mit den Medien die jungen Konsumenten mit immer raffinierteren Produktverbünden umgarnt. So ließ sich der Schluss ziehen, dass Kommerzialisierungstendenzen des Kinderfernsehens eingesetzt haben, die sich aus einer Abkehr von klassischen Werbeformen und einer Orientierung hin zu alternativen Werbe- und Vermarktungsstrategien ergeben haben

Enzyme engineering of a membrane-bound monooxygenase as key step of an artificial metabolic pathway towards Tulipalin A

Please click Additional Files below to see the full abstrac

Cosmic rays studied with a hybrid high school detector array

The LORUN/NAHSA system is a pathfinder for hybrid cosmic ray research combined with education and outreach in the field of astro-particle physics. Particle detectors and radio antennae were mainly setup by students and placed on public buildings. After fully digital data acquisition, coincidence detections were selected. Three candidate events confirmed a working prototype, which can be multiplied to extend further particle detector arrays on high schools.Comment: 10 pages, 6 figures. Nigl, A., Timmermans, C., Schellart, P., Kuijpers, J., Falcke, H., Horneffer, A., de Vos, C. M., Koopman, Y., Pepping, H. J., Schoonderbeek, G., Cosmic rays studied with a hybrid high school detector array, Europhysics News (EPN), Vol. 38, No. 5, accepted on 22/08/200

Chapter Operationalizing Heterogeneous Data-Driven Process Models for Various Industrial Sectors through Microservice-Oriented Cloud-Based Architecture

Industrial performance optimization increasingly makes the use of various analytical data-driven models. In this context, modern machine learning capabilities to predict future production quality outcomes, model predictive control to better account for complex multivariable environments of process industry, Bayesian Networks enabling improved decision support systems for diagnostics and fault detection are some of the main examples to be named. The key challenge is to integrate these highly heterogeneous models in a holistic system, which would also be suitable for applications from the most different industries. Core elements of the underlying solution architecture constitute highly decoupled model microservices, ensuring the creation of largely customizable model runtime environments. Deployment of isolated user-space instances, called containers, further extends the overall possibilities to integrate heterogeneous models. Strong requirements on high availability, scalability, and security are satisfied through the application of cloud-based services. Tieto successfully applied the outlined approach during the participation in FUture DIrections for Process industry Optimization (FUDIPO), a project funded by the European Commission under the H2020 program, SPIRE-02-2016

VLBI observations of jupiter with the initial test station of LOFAR and the nancay decametric array

AIMS: To demonstrate and test the capability of the next generation of low-frequency radio telescopes to perform high resolution observations across intra-continental baselines. Jupiter's strong burst emission is used to perform broadband full signal cross-correlations on time intervals of up to hundreds of milliseconds. METHODS: Broadband VLBI observations at about 20 MHz on a baseline of ~50000 wavelengths were performed to achieve arcsecond angular resolution. LOFAR's Initial Test Station (LOFAR/ITS, The Netherlands) and the Nancay Decametric Array (NDA, France) digitize the measured electric field with 12 bit and 14 bit in a 40 MHz baseband. The fine structure in Jupiter's signal was used for data synchronization prior to correlation on the time-series data. RESULTS: Strong emission from Jupiter was detected during snapshots of a few seconds and detailed features down to microsecond time-scales were identified in dynamic spectra. Correlations of Jupiter's burst emission returned strong fringes on 1 ms time-scales over channels as narrow as a hundred kilohertz bandwidth. CONCLUSIONS: Long baseline interferometry is confirmed at low frequencies, in spite of phase shifts introduced by variations in ionospheric propagation characteristics. Phase coherence was preserved over tens to hundreds of milliseconds with a baseline of ~700 km. No significant variation with time was found in the correlations and an estimate for the fringe visibility of 1, suggested that the source was not resolved. The upper limit on the source region size of Jupiter Io-B S-bursts corresponds to an angular resolution of ~3 arcsec. Adding remote stations to the LOFAR network at baselines up to thousand kilometers will provide 10 times higher resolution down to an arcsecond.Comment: 6 pages, 4 figures. Nigl, A., Zarka, P., Kuijpers, J., Falcke, H., Baehren, L., VLBI observations of Jupiter with the Initial Test Station of LOFAR and the Nancay Decametric Array, A&A, 471, 1099-1104, accepted on 31/05/200

Magnetic field strength and spectral distribution of six parsec-scale active galactic nuclei jets

We use observations of six "blazars" with the Very Long Baseline Array (VLBA), at eight frequencies (4.6, 5.1, 7.9, 8.9, 12.9, 15.4, 22.2, 43.1 GHz), to investigate the frequency-dependent position of their VLBI cores ("core-shift") and their overall jet spectral distribution. By cross-correlating the optically thin jet emission, we are able to accurately align the multi-frequency images of three of the jets (1418+546, 2007+777, 2200+420), whose core-shifts and spectra we find consistent with the equipartition regime of the Blandford & Konigl conical jet model, where the position of the radio core from the base of the jet follows $r_{core}\propto\nu^{-1}$. For the jet of 0954+658, we align the higher frequency images using our lower frequency measurements assuming equipartition in the radio core from 4.6-43 GHz. The jet emission of the other two sources in our sample (1156+295, 1749+096) is too sparse for our alignment technique to work. Using our measured core-shifts, we calculate equipartition magnetic field strengths of the order of 10's to 100's of mG in the radio cores of these four AGN from 4.6-43 GHz. Extrapolating our results back to the accretion disk and black hole jet-launching distances, we find magnetic field strengths consistent with those expected from theoretical models of magnetically powered jets.Comment: To match published version in MNRAS. Equation 5 corrected for typesetting error and references update

Operationalizing Heterogeneous Data-Driven Process Models for Various Industrial Sectors through Microservice-Oriented Cloud-Based Architecture

Industrial performance optimization increasingly makes the use of various analytical data-driven models. In this context, modern machine learning capabilities to predict future production quality outcomes, model predictive control to better account for complex multivariable environments of process industry, Bayesian Networks enabling improved decision support systems for diagnostics and fault detection are some of the main examples to be named. The key challenge is to integrate these highly heterogeneous models in a holistic system, which would also be suitable for applications from the most different industries. Core elements of the underlying solution architecture constitute highly decoupled model microservices, ensuring the creation of largely customizable model runtime environments. Deployment of isolated user-space instances, called containers, further extends the overall possibilities to integrate heterogeneous models. Strong requirements on high availability, scalability, and security are satisfied through the application of cloud-based services. Tieto successfully applied the outlined approach during the participation in FUture DIrections for Process industry Optimization (FUDIPO), a project funded by the European Commission under the H2020 program, SPIRE-02-2016