Fixed Point Indices and Manifolds with Collars

This paper concerns a formula which relates the Lefschetz number L(f) for a map f:M --> M' to the fixed point index I(f) summed with the fixed point index of a derived map on part of the boundary of M. Here M is a compact manifold and M' is M with a collar attached.Comment: Accepted for publication in Fixed Point Theory and Applications as part of the proceedings of the Newfoundland conference on fixed points, 200

Rats show individual preference for short-term choice of three human diets

A preference test was conducted to investigate whether rats could distinguish among three iso-energetic and iso-nitrogeneous human diets prepared with ingredients cultivated by each of three different farming strategies: LIminusP: low input of feritlizer without pesticides, LIplusP: lowinput of fertilicer and high input of pesticides and LHplusP: high input of fertilizer and high input of pesticides. The experimental diets were formulated to meet the NRC requirements for growing rats by mixing potatoes, carrots, peas, green kales, apples, and rapeseed oil. For five days, rats (N=27) had free access to each of the three diets, and consumption of each of the diets was recorded daily. Thereafter, rats were offered a standard laboratory chow until the test was repeated. The results indicated that the majority of the rats showed individual preference for the diets and behaved similarly on different experimental days (ρ = 0.63 in repetition 1 and ρ = 0.73 in repetition 2) and in the two repetitions (τ = 0.79). However, no clear difference among the dietary treatments could be obtained

Optofluidic circular grating distributed feedback dye laser

We demonstrate an optically pumped surface emitting optofluidic dye laser using a second-order circular grating distributed feedback resonator. We present a composite bilayer soft lithography technique specifically developed for the fabrication of our dye laser and investigate a hybrid polymer material system [poly(dimethylsiloxane)/perfluoropolyether] to construct high-resolution Bragg gratings. Our lasers emit single frequency light at low lasing thresholds of 6 µJ/mm^2. These optofluidic dye lasers can serve as low-cost and compact coherent light sources that are fully integrated within microfluidic analysis chips and provide an efficient approach to construct compact spectroscopy systems

Engaging Undergraduate Students in Transportation Studies through Simulating Transportation for Realistic Engineering Education and Training (STREET)

The practice of transportation engineering and planning has evolved substantially over the past several decades. A new paradigm for transportation engineering education is required to better engage students and deliver knowledge. Simulation tools have been used by transportation professionals to evaluate and analyze the potential impact of design or control strategy changes. Conveying complex transportation concepts can be effectively achieved by exploring them through simulation. Simulation is particularly valuable in transportation education because most transportation policies and strategies in the real world take years to implement with a prohibitively high cost. Transportation simulation allows learners to apply different control strategies in a risk-free environment and to expose themselves to transportation engineering methodologies that are currently in practice. Despite the advantages, simulation, however, has not been widely adopted in the education of transportation engineering. Using simulation in undergraduate transportation courses is sporadic and reported efforts have been focused on the upper-level technical elective courses. A suite of web-based simulation modules was developed and incorporated in the undergraduate transportation courses at University of Minnesota. The STREET (Simulating Transportation for Realistic Engineering Education and Training) research project was recently awarded by NSF (National Science Foundation) to develop web-based simulation modules to improve instruction in transportation engineering courses and evaluate their effectiveness. Our ultimate goal is to become the epicenter for developing simulation-based teaching materials, an active textbook, which offers an interactive learning environment to undergraduate students. With the hand-on nature of simulation, we hope to improve student understanding of critical concepts in transportation engineering and student motivation toward transportation engineering, and improve student retention in the field. We also would like to disseminate the results and teaching materials to other colleges to integrate the simulation modules in their curricula.Transportation Education and Training, Transportation Simulation, Roadway Geometry Design

Common Lunar Lander (CLL) Communication Subsystem Design

The communication subsystem is required to provide downlink for telemetry data and uplink for command data. It also provides Doppler/ranging for the state-vector generation. Detailed trades, system designs, and requirements analysis were performed to provide the most realistic estimates for the project

GraphMaps: Browsing Large Graphs as Interactive Maps

Algorithms for laying out large graphs have seen significant progress in the past decade. However, browsing large graphs remains a challenge. Rendering thousands of graphical elements at once often results in a cluttered image, and navigating these elements naively can cause disorientation. To address this challenge we propose a method called GraphMaps, mimicking the browsing experience of online geographic maps. GraphMaps creates a sequence of layers, where each layer refines the previous one. During graph browsing, GraphMaps chooses the layer corresponding to the zoom level, and renders only those entities of the layer that intersect the current viewport. The result is that, regardless of the graph size, the number of entities rendered at each view does not exceed a predefined threshold, yet all graph elements can be explored by the standard zoom and pan operations. GraphMaps preprocesses a graph in such a way that during browsing, the geometry of the entities is stable, and the viewer is responsive. Our case studies indicate that GraphMaps is useful in gaining an overview of a large graph, and also in exploring a graph on a finer level of detail.Comment: submitted to GD 201

Non-Nuclear, Low-Carbon, or Both? The Case of Taiwan

The Fukushima nuclear accident in Japan has renewed debates on the safety of nuclear power, possibly hurting the role of nuclear power in efforts to limit CO2 emissions. I develop a dynamic economy-wide model of Taiwan with a detailed set of technology options in the power sector to examine the implications of adopting different nuclear power policies on CO2 emissions and the economy. Absent a carbon mitigation target, limiting nuclear power has a small economic cost for Taiwan, but CO2 emissions may increase by more than 3.5% by 2035 when nuclear is replaced by fossil-based generation. With a low-carbon target of a 50% reduction from year 2000 levels by 2050, if the nuclear option and carbon sequestration are not viable, gas-fired power would provide almost 90% of electricity output due to the limited renewable resources. In particular, wind power would account for 1.6% to 4.9% of that output, depending on how it relies on other back-up capacities. With both non-nuclear and low-carbon policies, deploying carbon sequestration on fossil-based generation can significantly reduce the negative GDP impact on the economy. Lastly, lowering carbon mitigation costs further is possible with expanded nuclear capacity.The author gratefully acknowledges comments and suggestions from John Reilly, Frank Hsiao, Audrey Resutek, and seminar participants of the MIT EPPA meeting, and the financial support from the MIT Joint Program on the Science and Policy of Global Change. The Program is funded by the following institutions under various grants: the U.S. Department of Energy; the U.S. Environmental Protection Agency; the U.S. National Science Foundation; the U.S. National Aeronautics and Space Administration; the U.S. National Oceanic and Atmospheric Administration; the U.S. Federal Aviation Administration; the Electric Power Research Institute; and a consortium of industrial and foundation sponsors (for complete list see http://globalchange.mit.edu/sponsors/all)