Step-Indexed Logical Relations for Probability (long version)

It is well-known that constructing models of higher-order probabilistic programming languages is challenging. We show how to construct step-indexed logical relations for a probabilistic extension of a higher-order programming language with impredicative polymorphism and recursive types. We show that the resulting logical relation is sound and complete with respect to the contextual preorder and, moreover, that it is convenient for reasoning about concrete program equivalences. Finally, we extend the language with dynamically allocated first-order references and show how to extend the logical relation to this language. We show that the resulting relation remains useful for reasoning about examples involving both state and probabilistic choice.Comment: Extended version with appendix of a FoSSaCS'15 pape

The Use of Force Against Hegemonic Malcontents

Malcontents within international relations are small states that signal the decline of the hegemonic state. While not the direct cause of a hegemonic state‘s downfall, the malcontent is a sign that the hegemon is becoming weaker and the more malcontents is a symbol of the dwindling power of a hegemon. This work takes combines hegemonic theory and international relations theory to form a typology of malcontents. In addition this work introduces a futures analysis methodology that helps to quantify the impact that malcontents have on the hegemonic future of the United States. This typology divides malcontents into three specific categories, revolutionary, benign, and passive aggressive according to their approach to achieving their national goals. The futures analysis exercise gives results that show how malcontents are a part of a much larger decline in general. Malcontents help to demonstrate how weak the hegemon really is, further hastening its decline. The use of force against hegemonic malcontents is often the only policy choice left and it is often the worst policy decision that can be made

Adjustment of interaural-time-difference analysis to sound level

To localize low-frequency sound sources in azimuth, the binaural system compares the timing of sound waves at the two ears with microsecond precision. A similarly high precision is also seen in the binaural processing of the envelopes of high-frequency complex sounds. Both for low- and high-frequency sounds, interaural time difference (ITD) acuity is to a large extent independent of sound level. The mechanisms underlying this level-invariant extraction of ITDs by the binaural system are, however, only poorly understood. We use high-frequency pip trains with asymmetric and dichotic pip envelopes in a combined psychophysical, electrophysiological, and modeling approach. Although the dichotic envelopes cannot be physically matched in terms of ITD, the match produced perceptually by humans is very reliable, and it depends systematically on the overall sound level. These data are reflected in neural responses from the gerbil lateral superior olive and lateral lemniscus. The results are predicted in an existing temporal-integration model extended with a level-dependent threshold criterion. These data provide a very sensitive quantification of how the peripheral temporal code is conditioned for binaural analysis

Research & Development User Interface Engineering (UIE)

Flyer about User Interface Engineering (UIE) at the MPDL

Behavior of the Dripping Faucet over a Wide Range of the Flow Rate

The time interval of successive water-drips from a faucet was examined over a wide range of the flow rate. The dripping interval alternately exhibits a stable state and a chaotic state as the flow rate increases. In the stable state, the volume of the drip is kept constant at fixed flow rates, and the constant volume increases with the flow rate. In the chaotic state, in addition to a mechanics that the drip is torn by its own weight, the vibration of the drip on the faucet takes part in the strange behavior of the interval.Comment: 7 pages, 7 figures, to be published in J. Phys. Soc. Jpn vol 68-2(1999

Sustainability science graduate students as boundary spanners

Graduate training in sustainability science (SS) focuses on interdisciplinary research, stakeholder-researcher partnerships, and creating solutions from knowledge. But becoming a sustainability scientist also requires specialized training that addresses the complex boundaries implicit in sustainability science approaches to solving social-ecological system challenges. Using boundary spanning as a framework, we use a case study of the Sustainability Solutions Initiative (SSI) at the University of Maine to explicate key elements for graduate education training in SS. We used a mixed-methods approach, including a quantitative survey and autoethnographic reflection, to analyze our experiences as SSI doctoral students. Through this research, we identified four essential SS boundaries that build on core sustainability competencies which need to be addressed in SS graduate programs, including: disciplines within academia, students and their advisors, researchers and stakeholders, and place-based and generalizable research. We identified key elements of training necessary to help students understand and navigate these boundaries using core competencies. We then offer six best practice recommendations to provide a basis for a SS education framework. Our reflections are intended for academic leaders in SS who are training new scientists to solve complex sustainability challenges. Our experiences as a cohort of doctoral students with diverse academic and professional backgrounds provide a unique opportunity to reflect not only on the challenges of SS but also on the specific needs of students and programs striving to provide solutions