The Framing of Games and the Psychology of Strategic Choice

Psychological game theory can provide a rational choice explanation of framing effects; frames influence beliefs, and beliefs influence motivations. We explain this point theoretically, and explore its empirical relevance experimentally. In a 2×2-factorial framing design of one-shot public good experiments we show that frames affect subject’s first- and second-order beliefs, and contributions. From a psychological game-theoretic framework we derive two mutually compatible hypotheses about guilt aversion and reciprocity under which contributions are related to second- and first-order beliefs, respectively. Our results are consistent with either.Framing; psychological games; guilt aversion; reciprocity; public good games; voluntary cooperation

Fast Bayesian Optimization of Machine Learning Hyperparameters on Large Datasets

Bayesian optimization has become a successful tool for hyperparameter optimization of machine learning algorithms, such as support vector machines or deep neural networks. Despite its success, for large datasets, training and validating a single configuration often takes hours, days, or even weeks, which limits the achievable performance. To accelerate hyperparameter optimization, we propose a generative model for the validation error as a function of training set size, which is learned during the optimization process and allows exploration of preliminary configurations on small subsets, by extrapolating to the full dataset. We construct a Bayesian optimization procedure, dubbed Fabolas, which models loss and training time as a function of dataset size and automatically trades off high information gain about the global optimum against computational cost. Experiments optimizing support vector machines and deep neural networks show that Fabolas often finds high-quality solutions 10 to 100 times faster than other state-of-the-art Bayesian optimization methods or the recently proposed bandit strategy Hyperband

Probabilistic Linear Solvers: A Unifying View

Several recent works have developed a new, probabilistic interpretation for numerical algorithms solving linear systems in which the solution is inferred in a Bayesian framework, either directly or by inferring the unknown action of the matrix inverse. These approaches have typically focused on replicating the behavior of the conjugate gradient method as a prototypical iterative method. In this work surprisingly general conditions for equivalence of these disparate methods are presented. We also describe connections between probabilistic linear solvers and projection methods for linear systems, providing a probabilistic interpretation of a far more general class of iterative methods. In particular, this provides such an interpretation of the generalised minimum residual method. A probabilistic view of preconditioning is also introduced. These developments unify the literature on probabilistic linear solvers, and provide foundational connections to the literature on iterative solvers for linear systems

Das FFH- und Vogelschutzgebiet Glücksburger Heide : Naturausstattung und Management

Die Glücksburger Heide liegt im äußersten Osten des Landes Sachsen-Anhalt. Innerhalb des Geltungsbereiches der FFH-Richtlinie gehört das Gebiet biogeographisch zur kontinentalen Region und wird naturräumlich als Teil des „Nordostdeutschen Tieflandes“ zur Einheit D11 „Fläming“ (Ssymank & Hauke in BfN 1998) und zur Landschaftseinheit 1.8 „Südliches Fläming-Hügelland“ (aktuelle Landschaftsgliederung Sachsen Anhalts in Reichhoff et al. 2001) gerechnet. Die Region ist insgesamt dünn besiedelt und stellt einen relativ unzerschnittenen Raum dar. Die Glücksburger Heide in den Grenzen des ehemaligen Truppenübungsplatzes ist Teil eines weitestgehend zusammenhängenden, zwischen Jessen bis Seehausen und Linda ausgedehnten Forstkomplexes von insgesamt mehr als 10.000 ha Fläche

Mirror suspensions for the Glasgow Sagnac speed meter

A new era of gravitational wave astronomy has begun with the first direct detections of gravitational waves from the collision of binary black holes and a binary neutron star system. The scientific outcomes from these detections have been magnificent, however in order to increase the event rates for known sources, to be sensitive to new sources, to detect sources at greater distances, and to increase the signal to noise ratio for better extraction of source parameters, further research is required to increase the detectors sensitivity. The Advanced LIGO and Advanced Virgo detectors that enabled these first detections will ultimately be limited in their sensitivity by reaching the standard quantum limit (SQL). One novel technique to reduce the influence of quantum radiation pressure noise in a measurement of strain between two test masses is the speed meter topology. As a proof of concept experiment the Glasgow Sagnac Speed Meter experiment aims to show a reduction in quantum radiation pressure noise compared to an equivalent Michelson interferometer at audio-band frequencies. Two triangular cavities are the core of the experiment and consist of two 100g end test masses and one 1g input test masses per cavity, all suspended from multistage pendulums. In this combination the whole Sagnac Speed Meter experiment should be limited by quantum radiation pressure noise from about 100Hz to 1kHz and it is expected to achieve a reduction of quantum radiation pressure noise by a factor of 3-5 compared to an equivalent Michelson interferometer. This thesis presents the development, design, commissioning and testing of the three main types of suspensions in the Sagnac Speed Meter experiment. The longitudinal displacement noise requirement for both cavity suspension types is <1.5 x 10-18m/√Hz over the measurement band between 100Hz and about 1kHz. In order to isolate the mirrors from seismic ground motion in the Sagnac Speed Meter experiment, they are suspended from multistage pendulums, resulting ideally in a 1/f^2n response for n pendulum stages above the pendulums rigid body modes. Reduction of thermal noise in the suspension elements (suspension thermal noise) is achieved by the introduction of high quality-factor materials in the lowest pendulum stage, making it fully monolithic. The 100g end test mass suspension is based on an existing design, originally developed for the AEI 10m prototype, as a triple suspension with two stages of vertical blade springs and a fully monolithic lowest pendulum stage. The 1g input test mass suspension, designed as a quadruple pendulum with a fully monolithic lowest pendulum stage, utilises the same vertical blade springs and top mass as the 100g end test mass suspension. The quadruple pendulum design enables passive damping of test mass motion at the penultimate stage. As passive damping introduces force noise due to thermal noise, a switchable passive damping system was developed and tested to mitigate limitation by this force noise. The auxiliary suspension, a double pendulum, serves to suspend the mirrors in the experiment that guide the beam towards the Sagnac Speed Meter, in between the cavities, and towards the balanced homodyne detector. As these are not part of the cavities, the longitudinal displacement noise requirement can be relaxed to <8 x 10-15m/√Hz at 100Hz. The pendulum dynamics of the auxiliary and 100g end test mass suspension were measured in an optical lever set up and, in case of the auxiliary suspension, additionally with a vibrometer. With these measurements, the models were adjusted and could be used to estimate the longitudinal displacement noise due to coupling from seismic ground motion and thus verify the required performance of the suspensions. The research conducted in this thesis is an important step towards establishing the speed meter topology for consideration in future gravitational wave detectors. The developments in the scope of the monolithic assembly for the 100g end test masses will be applied to the AEI 10m prototype in order to enable sub-SQL measurements

A new type of quantum speed meter interferometer: measuring speed to search for intermediate mass black holes

The recent discovery of gravitational waves (GW) by LIGO has impressively launched the novel field of gravitational astronomy and it allowed us to glimpse at exciting objects we could so far only speculate about. Further sensitivity improvements at the low frequency end of the detection band of future GW observatories rely on quantum non-demolition (QND) methods to suppress fundamental quantum fluctuations of the light fields used to readout the GW signal. Here we invent a novel concept of how to turn a conventional Michelson interferometer into a QND speed meter interferometer with coherently suppressed quantum back-action noise by using two orthogonal polarisations of light and an optical circulator to couple them. We carry out a detailed analysis of how imperfections and optical loss influence the achievable sensitivity and find that the configuration proposed here would significantly enhance the low frequency sensitivity and increase the observable event rate of binary black hole coalescences in the range of $10^2-10^3 M_\odot$ by a factor of up to $\sim300$.Comment: 8 pages, 5 figures. Modified figures and text in v

Open-source image reconstruction of super-resolution structured illumination microscopy data in ImageJ

Müller M, Mönkemöller V, Hennig S, Hübner W, Huser T. Open-source image reconstruction of super-resolution structured illumination microscopy data in ImageJ. Nature Communications. 2016;7(1): 10980

Sub-system mechanical design for an eLISA optical bench

We present the design and development status of the opto-mechanical sub-systems that will be used in an experimental demonstration of imaging systems for eLISA. An optical bench test bed design incorporates a Zerodur® baseplate with lenses, photodetectors, and other opto-mechanics that must be both adjustable - with an accuracy of a few micrometers - and stable over a 0 to 40°C temperature range. The alignment of a multi-lens imaging system and the characterisation of the system in multiple degrees of freedom is particularly challenging. We describe the mechanical design of the precision mechanisms, including thermally stable flexure-based optical mounts and complex multi-lens, multi-axis adjuster mechanisms, and update on the integration of the mechanisms on the optical bench