Der Pulvermaar-Vulkan

Das etwa 20 000 Jahre alte Pulvermaar in der Westeifel besitzt einen 72 m tiefen, zentral liegenden See und einen stellenweise mindestens 45 m mächtigen Tuffwall. Durch seinen außergewöhnlich guten Erhaltungszustand nimmt es eine Sonderstellung ein. Um auch den Tiefbau dieser Struktur besser kennenzulernen, wurden geophysikalische Messungen mit dem Ziel einer dreidimensionalen Modellierung durchgeführt. Über beides wird in dieser Arbeit berichtet. Den Schwerpunkt der geophysikalischen Untersuchungen bildet ein Gravimetrieprogramm mit der Erstellung einer Schwerekarte des Pulvermaars und seiner Umgebung. Im Rahmen dieser Schweremessungen hat der Einsatz des GPS-Systems zur Vermessung ein besonderes Gewicht. Die Magnetfeldmessungen der Totalintensität konzentrieren sich mit einem dichten Meßnetz auf den Seebereich (Messungen im Boot). Mit Widerstands-Tiefensondierungen der Geoelektrik wird versucht, zu einer präziseren Bestimmung der Tuffmächtigkeiten zu gelangen. Die gewonnene Schwerekarte dient einer dreidimensionalen Modellierung auf der Basis der Freiluftanomalie mit dem Programm IGMAS. Die verhältnismäßig kleine (negative) Schwere-anomalie von 1 - 2 mGal über dem Pulvermaar läßt vermuten, daß ein Basaltkörper in das Diatrem eingebettet ist und zur kleinen Amplitude beiträgt. Die Magnetfeldmessungen er-härten diese Vorstellung; das Ergebnis einer einfachen Modellierung für ein diametrales Profil ist mit einem 40 m mächtigen Basaltkörper grob 120 m unter Seeoberfläche ver-träglich. Die Ergebnisse der gravimetrischen und magnetischen Modellierung, die Mächtigkeitsab-schätzungen für die pyroklastischen Ablagerungen aufgrund der Geoelektrik-Messungen sowie die Einbeziehung einer Volumenkalkulation für die Pyroklastika führen zu einem detaillierten Modell für das Pulvermaar, das sich insbesondere durch ein 2000 m tief reichendes Diatrem auszeichnet. Eine Bearbeitung des Schwerefeldes mit der Berechnung von Gradientenfeldern führt zu einem bisher von Maaren nicht bekannten Ergebnis: Um das Pulvermaar herum existiert ein Hof erniedrigter Dichte mit einem Durchmesser von grob 2 km. Als Ursache wird eine Auf-lockerung des Gesteins durch Streß-Wellen angenommen, die ihren Ursprung in den wiederholten starken Eruptionen der Maar-Entstehung haben. Ebenfalls die Gradienten-felder der Gravimetrie zeigen Zusammenhänge zwischen der Struktur des Maares und der regionalen Tektonik auf.The Pulvermaar is located in the Westeifel volcanic field. It is roughly 20000 years old and contains a 72 m deep, centrally situated maar lake as well as a partially at least 45 m thick tuff-rim. The Pulvermaar is very exceptional due to its good state of preservation. To learn more about the underground body of this structure, geophysical investigations were carried out aiming at a three-dimensional modeling. The core of the geophysical investigations represented a gravimetrical program in order to create a gravitational anomaly map of the Pulvermaar and its surroundings. The use of the GPS-system was of special importance for the gravimetrical measurements. The magnetic field measurements of the total intensity were mainly conducted in a fine pattern all over the lake-side (measurements on a boat). With the help of geoelectrical resistivity soundings one tried to precisely determine the thickness of the tuff deposits. The resulting gravity anomaly map serves a three-dimensional modeling based on free air anomaly with the software-program IGMAS. The relatively small (negative) gravitational anomaly of 1-2 mGal above the Pulvermaar leads to the assumption that a basaltic body is embedded in the diatreme and contributes to the small amplitude. The magnetic field measurements support this conception. The result of a simple modeling of a diametrical profile fits to a 40 m thick basaltic body located in about 120 m below the surface of the lake. The gravimetric and magnetic modeling, the estimation of the thickness of the pyroclastic deposits based on geoelectrical measurements, and the calculation of the volumina of the pyroclastic rocks lead to a detailled model for the Pulvermaar. This is espeacially characterized by a 2000 m deep diatreme. The processing of the gravity field by a calculation of its gradient fields leads to a result which is yet unknown for maarvolcanoes: the Pulvermaar is surrounded by a 2 km-diameter halo of reduced density. This can be explained by a relaxation of the rocks caused by stress-waves which originate from the repeatedly heavy eruptions during the formation of maarvolcanoe. Also, the gradients fields of the gravity show correlations between the structure of the maarvolcanoe and the regional tectonic

Sie können wie die Knaben, aber sie müssen anders erzogen werden: August Hermann Niemeyer (1754-1828) und die Töchtererziehung

Im Folgenden soll es um Überlegungen von August Hermann Niemeyer (1754-1828), dem Urenkel August Hermann Franckes und Leiter der Franckeschen Stiftungen, zur Mädchenerziehung sowie deren eventuelle Anwendung im familiären Raum gehen. Zunächst wurde ein ideengeschichtlicher Zugang gewählt, um seine auffallend progressiven Ausführungen zum Mädchenschulwesen den konservativen, auf Geschlechtsstereotypen beruhenden Gedanken zur Erziehung der Töchter gegenüberzustellen. Dies erfolgt anhand seines Werkes Grundsätze der Erziehung und des Unterrichts. Im zweiten Teil wird mit Hilfe eines historisch-anthropologischen Ansatzes der Frage nachgegangen, wie Niemeyers Ehefrau Agnes Wilhelmine ihre familiären Aufgaben unter Berücksichtigung der Rollenerwartungen gestaltete und inwiefern sich in diesen eine Rückkopplung an die Grundsätze widerspiegeln. (DIPF/Orig.)The article is concerned with August Hermann Niemeyer’s ideas about the education of girls and young women. Niemeyer (1754-1828) was the great-grandson of August Hermann Francke and the chairman of the Francke Foundation in Halle. Not only his theory will be focussed on, but also the interrelationship between his theory and his family, in particular his wife, who was known to expand the conservative role ascription of that time. First, using an approach based on historical conception development, Niemeyer’s progressive opinion on girl’s schools will be contrasted to his conservative and stereotypical attitude towards the “upbringing of the daughters”. In the second part of this article, the relationship between his wife’s daily routines and his theory will be examined. Using the perspective of historical anthropology, it was possible to reconstruct how Agnes Wilhelmine Niemeyer arranged her own female role while taking August Hermann Niemeyer’s theory into consideration. (DIPF/Orig.

5-dimensional Quantum Gravity Effects in Exclusive Double Diffractive Events

The experimentally measurable effects related to extra dimensional gravity in a RS-type brane world are estimated. Two options of the RS framework (namely, with small and large curvature) are considered. It is shown that both can be detected by the joint experiment of the CMS and TOTEM Collaborations at the LHC.Comment: 11 pages, 6 figures, 4 tables, acknowledgments are adde

An introduction to Lie group integrators -- basics, new developments and applications

We give a short and elementary introduction to Lie group methods. A selection of applications of Lie group integrators are discussed. Finally, a family of symplectic integrators on cotangent bundles of Lie groups is presented and the notion of discrete gradient methods is generalised to Lie groups

Unpacking changes in mangrove social-ecological systems: lessons from Brazil, Zanzibar, and Vietnam

Mangroves provide multiple benefits, from carbon storage and shoreline protection to food and energy for natural resource-dependent coastal communities. However, they are coming under increasing pressure from climate change, coastal development, and aquaculture. There is increasing need to better understand the changes mangroves face and whether these changes differ or are similar in different parts of the world. Using a multiple case study approach, focused on Vietnam, Zanzibar, and Brazil, this research analyzed the drivers, pressures, states, impacts, and responses (DPSIR) of mangrove systems. A qualitative content analysis was used on a purposively sampled document set for each country to identify and collate evidence under each of the DPSIR categories. Population growth and changing political and economic processes were key drivers across the three countries, leading to land use change and declining states of mangroves. This had an impact on the delivery of regulatory and provisioning ecosystem services from mangroves and on the welfare of coastal communities. Responses have been predominantly regulatory and aim to improve mangrove states, but without always considering ecosystem services or the consequences for welfare. The issue of scale emerged as a critical factor with drivers, pressures, impacts, and responses operating at different levels (from international to local), with consequences for response effectiveness

The Magnus expansion and some of its applications

Approximate resolution of linear systems of differential equations with varying coefficients is a recurrent problem shared by a number of scientific and engineering areas, ranging from Quantum Mechanics to Control Theory. When formulated in operator or matrix form, the Magnus expansion furnishes an elegant setting to built up approximate exponential representations of the solution of the system. It provides a power series expansion for the corresponding exponent and is sometimes referred to as Time-Dependent Exponential Perturbation Theory. Every Magnus approximant corresponds in Perturbation Theory to a partial re-summation of infinite terms with the important additional property of preserving at any order certain symmetries of the exact solution. The goal of this review is threefold. First, to collect a number of developments scattered through half a century of scientific literature on Magnus expansion. They concern the methods for the generation of terms in the expansion, estimates of the radius of convergence of the series, generalizations and related non-perturbative expansions. Second, to provide a bridge with its implementation as generator of especial purpose numerical integration methods, a field of intense activity during the last decade. Third, to illustrate with examples the kind of results one can expect from Magnus expansion in comparison with those from both perturbative schemes and standard numerical integrators. We buttress this issue with a revision of the wide range of physical applications found by Magnus expansion in the literature.Comment: Report on the Magnus expansion for differential equations and its applications to several physical problem