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

Energy-preserving splitting integrators for sampling from Gaussian distributions with Hamiltonian Monte Carlo method

The diffusive behaviour of simple random-walk proposals of many Markov Chain Monte Carlo (MCMC) algorithms results in slow exploration of the state space making inefficient the convergence to a target distribution. Hamiltonian/Hybrid Monte Carlo (HMC), by introducing fictious momentum variables, adopts Hamiltonian dynamics, rather than a probability distribution, to propose future states in the Markov chain. Splitting schemes are numerical integrators for Hamiltonian problems that may advantageously replace the St\"ormer-Verlet method within HMC methodology. In this paper a family of stable methods for univariate and multivariate Gaussian distributions, taken as guide-problems for more realistic situations, is proposed. Differently from similar methods proposed in the recent literature, the considered schemes are featured by null expectation of the random variable representing the energy error. The effectiveness of the novel procedures is shown for bivariate and multivariate test cases taken from the literature

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.

Will climate change be harmful for small tropical islands? The case of Fernando de Noronha Archipelago, Brazil

The Fernando de Noronha archipelago is a key site for biodiversity conservation, besides being one of the most searched destinies for ecotourism in Brazil. We present the first study focusing on the evaluation of this important archipelago’s exposure to climate change.  Our metric was based on the differences between current and future predictions of climatic and bioclimatic variables obtained from the WorldClim dataset. For the predictions, we considered two models of radiative forcing, the first optimistic and the second a business-as-usual scenario of greenhouse gases emissions. We showed an increase in average temperature and decrease in annual precipitation for the archipelago, although for the driest period of the year the precipitation is likely to increase. We also recovered a decrease in differences between interannual temperature variation and diurnal temperature variation, indicating a shift in the seasonality patterns. These changes can be potentially harmful to local biodiversity and consequently to local economy, since it is based on touristic activities that involves natural environments. The maintenance of local vegetation cover is likely to be a good strategy to avoid the local increase of environmental temperature, however, a global commitment to decrease the greenhouse gases emissions is paramount to avoid a potential collapse of small islands around the world, including the Fernando de Noronha archipelago

On the dynamics of a generalized predator-prey system with Z-type control.

We apply the Z-control approach to a generalized predator prey system and consider the specific case of indirect control of the prey population. We derive the associated Z-controlled model and investigate its properties from the point of view of the dynamical systems theory. The key role of the design parameter A. for the successful application of the method is stressed and related to specific dynamical properties of the Z-controlled model. Critical values of the design parameter are also found, delimiting the lambda-range for the effectiveness of the Z-method. Analytical results are then numerically validated by the means of two ecological models: the classical Lotka-Volterra model and a model related to a case study of the wolf wild boar dynamics in the Alta Murgia National Park. Investigations on these models also highlight how the Z-control method acts in respect to different dynamical regimes of the uncontrolled model. (C) 2016 The Authors. Published by Elsevier Inc

Ressocialização do condenado por meio do trabalho

A ressocialização do apenado é algo que precisa ser reanalisado diante do contexto atual do sistema carcerário, pois o ambiente a qual este apenado esta submetido revela-se claramente incapaz de promover a sua ressocialização por si só. É diante desta realidade que se pode afirmar que o trabalho aparece como um mecanismo de eficácia e grande importância quando nos referimos ao processo de ressocialização do condenado. Desta forma este trabalho acadêmico possui como função precípua a demonstração de que este é um caminho viável e que pode também acarretar em varias consequências não só para o próprio apenado, como também para a sociedade e para o Estado