Visual control of flight speed in Drosophila melanogaster

Flight control in insects depends on self-induced image motion (optic flow), which the visual system must process to generate appropriate corrective steering maneuvers. Classic experiments in tethered insects applied rigorous system identification techniques for the analysis of turning reactions in the presence of rotating pattern stimuli delivered in open-loop. However, the functional relevance of these measurements for visual free-flight control remains equivocal due to the largely unknown effects of the highly constrained experimental conditions. To perform a systems analysis of the visual flight speed response under free-flight conditions, we implemented a `one-parameter open-loop' paradigm using `TrackFly' in a wind tunnel equipped with real-time tracking and virtual reality display technology. Upwind flying flies were stimulated with sine gratings of varying temporal and spatial frequencies, and the resulting speed responses were measured from the resulting flight speed reactions. To control flight speed, the visual system of the fruit fly extracts linear pattern velocity robustly over a broad range of spatio–temporal frequencies. The speed signal is used for a proportional control of flight speed within locomotor limits. The extraction of pattern velocity over a broad spatio–temporal frequency range may require more sophisticated motion processing mechanisms than those identified in flies so far. In Drosophila, the neuromotor pathways underlying flight speed control may be suitably explored by applying advanced genetic techniques, for which our data can serve as a baseline. Finally, the high-level control principles identified in the fly can be meaningfully transferred into a robotic context, such as for the robust and efficient control of autonomous flying micro air vehicles

The Role of State and Provincial Governments in Canada-U.S. Sectoral Integration

state and provincial governments and sectoral integratio

Strategic Choices and Changes in the International Political Economy

Europe 1992 has become a major focus of attention for the Western media, because if all goes as planned, a unified and integrated common market of 12 nations and 320 million consumers will be created, a market running from the mountains of Mourne to the Peloponnese with a GNP rivaling that of the United States. Further east, the Kremlin is determined to put the Soviet Union\u27s tattered economic house in order under Gorbachev’s much ballyhooed perestroika strategy. And along Asia\u27s Pacific rim, rapid growth may permit this region to match the productive capacity of both the United States and the European Community within the next two decades

Flight investigation of methods for implementing noise-abatement landing approaches

Flight tests and simulation of steep noise reducing landing approaches with jet transpor

Welcoming New Mainers: Local Economic Development and its Effects on the Politics of Immigration

This thesis examines the policy and rhetoric directed toward immigrants from elite municipal actors in Maine’s two largest metropolitan areas: Lewiston and Portland. These cities, situated in one of the least diverse states in the nation, have recently seen large changes to their demographic makeups. While both share a similar history, in recent years they have diverged in terms of their politicians’ policy and rhetoric toward immigrants. The scholarship on immigration in the United States suggests that certain factors, such as the levels of economic anxiety present in an area, the existence of a so-called “creative class,” and an infrastructure of support services can influence how receptive a city’s existing residents may be to anti-immigrant rhetoric. This thesis employs a historical institutionalist framework emphasizing critical junctures, path dependency, and political entrepreneurship to account for the distinct economic development undertaken in Lewiston and Portland since the mid-twentieth century. By analyzing the histories of Maine’s two largest cities and the norm-breaking behavior of the former Governor of Maine, Paul LePage, this thesis offers an explanation as to why anti-immigrant rhetoric is more salient in certain locales