Wave Propagation in the Ground and Isolation Measures

The first part of this report deals with wave propagation in the ground. Special attention is given to the radiation of waves from a source and on the effect of layering or continuous variation of the shear modulus in the soil on travelling waves. In the second part, vibration isolation measures are described, such as open or infilled trenches and rows of bore holes or piles. The results of different theoretical and experimental investigations are compared. Finally, recently developed isolation measures are presented

Stochastic optimization of a cold atom experiment using a genetic algorithm

We employ an evolutionary algorithm to automatically optimize different stages of a cold atom experiment without human intervention. This approach closes the loop between computer based experimental control systems and automatic real time analysis and can be applied to a wide range of experimental situations. The genetic algorithm quickly and reliably converges to the most performing parameter set independent of the starting population. Especially in many-dimensional or connected parameter spaces the automatic optimization outperforms a manual search.Comment: 4 pages, 3 figure

Experimental and analytic studies of the triggered lightning environment of the F106B

The triggered lightning environment of the F106B aircraft is investigated. Scale modeling of the F106B with a metallized model was done to measure electric field enhancement factors on the aircraft and on canonically shaped conducting objects. These are then compared to numerically determined quantities. Detailed numerical modeling is done of the development of the triggered lightning channel. This is done using nonlinear air chemistry models to model a variety of physical phenomena which occur in a triggered lightning event. The effect of a triggered lightning strike on internal wires in the F106B is investigated using finite difference models and transmission line models to calculate the electromagnetic coupling of lightning currents through seams and joints of the aircraft to internal cables. Time domain waveforms are computed and compared to measured waveforms. The effect of thunderstorm particles on the initial triggering of a lightning strike is investigated. The electric field levels needed to cause air breakdown in the presence and absence of thunderstorm particles are calculated. This is done as a function of the size, shape, and density of the particles

Far-infrared absorption in parallel quantum wires with weak tunneling

We study collective and single-particle intersubband excitations in a system of quantum wires coupled via weak tunneling. For an isolated wire with parabolic confinement, the Kohn's theorem guarantees that the absorption spectrum represents a single sharp peak centered at the frequency given by the bare confining potential. We show that the effect of weak tunneling between two parabolic quantum wires is twofold: (i) additional peaks corresponding to single-particle excitations appear in the absorption spectrum, and (ii) the main absorption peak acquires a depolarization shift. We also show that the interplay between tunneling and weak perpendicular magnetic field drastically enhances the dispersion of single-particle excitations. The latter leads to a strong damping of the intersubband plasmon for magnetic fields exceeding a critical value.Comment: 18 pages + 6 postcript figure

Ranking local climate policy: assessing the mitigation and adaptation activities of 104 German cities

Climate mitigation and climate adaptation are crucial tasks for urban areas and can involve synergies as well as trade-offs. However, few studies have examined how mitigation and adaptation efforts relate to each other in a large number of differently sized cities, and therefore we know little about whether forerunners in mitigation are also leading in adaptation or if cities tend to focus on just one policy field. This article develops an internationally applicable approach to rank cities on climate policy that incorporates multiple indicators related to (1) local commitments on mitigation and adaptation, (2) urban mitigation and adaptation plans and (3) climate adaptation and mitigation ambitions. We apply this method to rank 104 differently sized German cities and identify six clusters: climate policy leaders, climate adaptation leaders, climate mitigation leaders, climate policy followers, climate policy latecomers and climate policy laggards. The article seeks explanations for particular cities’ positions and shows that coping with climate change in a balanced way on a high level depends on structural factors, in particular city size, the pathways of local climate policies since the 1990s and funding programmes for both climate mitigation and adaptation

Critical phenomena: 150 years since Cagniard de la Tour

Critical phenomena were discovered by Cagniard de la Tour in 1822, who died 150 years ago. In order to mark this anniversary, the context and the early history of his discovery is reviewed. We then follow with a brief sketch of the history of critical phenomena, indicating the main lines of development until the present date. Os fen\'omenos cr\'{\i}ticos foram descobertos pelo Cagniard de la Tour em Paris em 1822. Para comemorar os 150 anos da sua morte, o contexto e a hist\'oria initial da sua descoberta \'e contada. Conseguimos com uma descri\c{c}\~ao breve da hist\'oria dos fen\'emenos cr\'{\i}ticos, indicando as linhas principais do desenvolvimento at\'e o presente.Comment: Latex2e, 8 pp, 3 eps figures include

Boosted three-dimensional black-hole evolutions with singularity excision

Binary black hole interactions provide potentially the strongest source of gravitational radiation for detectors currently under development. We present some results from the Binary Black Hole Grand Challenge Alliance three- dimensional Cauchy evolution module. These constitute essential steps towards modeling such interactions and predicting gravitational radiation waveforms. We report on single black hole evolutions and the first successful demonstration of a black hole moving freely through a three-dimensional computational grid via a Cauchy evolution: a hole moving ~6M at 0.1c during a total evolution of duration ~60M

Intentionality and visibility in state- and society-led climate approaches: towards a more comprehensive understanding of local adaptation initiatives

Research into local climate adaptation has often focused on highly visible, intentional public policies that seek to improve resilience to climate threats, or how societal actors have reacted to changing climatic conditions. We argue that these approaches neglect a range of unintentional and/or hidden initiatives, which deliver implicit and/or hitherto under-appreciated adaptation benefits. We present an analytical framework to organise studies of these under-explored initiatives, which advances social scientific conceptualisations of what local climate adaptation consists of and provides a heuristic for selecting appropriate methods of enquiry to examine it. Drawing on empirical research into the adaptation activities of municipalities and small businesses in Germany, we apply this framework to expand our knowledge of how communities are building climate resilience, gain a better understanding of the full range of adaptation activities within individual localities, and pose questions about the role of state and societal actors in addressing common problems

Intentionality and visibility in state- and society-led climate approaches: towards a more comprehensive understanding of local adaptation initiatives

Research into local climate adaptation has often focused on highly visible, intentional public policies that seek to improve resilience to climate threats or how societal actors have reacted to changing climatic conditions. We argue that these approaches neglect a range of unintentional and/or hidden initiatives, which deliver implicit and/or hitherto under-appreciated adaptation benefits. We present an analytical framework to organise studies of these under-explored initiatives, which advances social scientific conceptualisations of what local climate adaptation consists of and provides a heuristic for selecting appropriate methods of enquiry to examine it. Drawing on empirical research into the adaptation activities of municipalities and small businesses in Germany, we apply this framework to expand our knowledge of how communities are building climate resilience, gain a better understanding of the full range of adaptation activities within individual localities, and pose questions about the role of state and societal actors in addressing common problems.</p