The L^2 signature of torus knots

We find a formula for the L2 signature of a (p,q) torus knot, which is the integral of the omega-signatures over the unit circle. We then apply this to a theorem of Cochran-Orr-Teichner to prove that the n-twisted doubles of the unknot, for n not 0 or 2, are not slice. This is a new proof of the result first proved by Casson and Gordon.Comment: 11 pages, Version 2 contains a note explaining that the main theorem of the paper has already been proved in earlier work by Kirby and Melvi

Strategies for automatic planning: A collection of ideas

The main goal of the Jet Propulsion Laboratory (JPL) is to obtain science return from interplanetary probes. The uplink process is concerned with communicating commands to a spacecraft in order to achieve science objectives. There are two main parts to the development of the command file which is sent to a spacecraft. First, the activity planning process integrates the science requests for utilization of spacecraft time into a feasible sequence. Then the command generation process converts the sequence into a set of commands. The development of a feasible sequence plan is an expensive and labor intensive process requiring many months of effort. In order to save time and manpower in the uplink process, automation of parts of this process is desired. There is an ongoing effort to develop automatic planning systems. This has met with some success, but has also been informative about the nature of this effort. It is now clear that innovative techniques and state-of-the-art technology will be required in order to produce a system which can provide automatic sequence planning. As part of this effort to develop automatic planning systems, a survey of the literature, looking for known techniques which may be applicable to our work was conducted. Descriptions of and references for these methods are given, together with ideas for applying the techniques to automatic planning

On the concordance orders of knots

This thesis develops some general calculational techniques for finding the orders of knots in the topological concordance group C. The techniques currently available in the literature are either too theoretical, applying to only a small number of knots, or are designed to only deal with a specific knot. The thesis builds on the results of Herald, Kirk and Livingston [HKL10] and Tamulis [Tam02] to give a series of criteria, using twisted Alexander polynomials, for determining whether a knot is of infinite order in C. There are two immediate applications of these theorems. The first is to give the structure of the subgroups of the concordance group C and the algebraic concordance group G generated by the prime knots of 9 or fewer crossings. This should be of practical value to the knot-theoretic community, but more importantly it provides interesting examples of phenomena both in the algebraic and geometric concordance groups. The second application is to find the concordance orders of all prime knots with up to 12 crossings. At the time of writing of this thesis, there are 325 such knots listed as having unknown concordance order. The thesis includes the computation of the orders of all except two of these. In addition to using twisted Alexander polynomials to determine the concordance order of a knot, a theorem of Cochran, Orr and Teichner [COT03] is applied to prove that the n-twisted doubles of the unknot are not slice for n not 0 or 2. This technique involves analysing the `second-order' invariants of a knot; that is, slice invariants (in this case, signatures) of a set of metabolising curves on a Seifert surface for the knot. The thesis extends the result to provide a set of criteria for the n-twisted double of a general knot K to be slice; that is, of order 0 in C.Comment: 146 pages, full PhD thesi

The impact of bidding aggregation levels on truckload rates

Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2010.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 79-80).The objective of this thesis was to determine if line-haul rates are impacted by bid type, and if aggregation of bidding lanes can reduce costs for both shippers and carriers. Using regression analysis, we developed a model to isolate and test the cost effects that influence line-haul rate for long-haul shipments. We have determined that aggregation of low-volume lanes from point-to-point lanes to aggregated lanes can provide costs savings when lanes with origins and destinations in close proximity to each other can be bundled. In addition, bidding out region-to-region lanes can supplement point-to-point lanes by reducing the need to turn to the spot market. The model shows that bundling lanes can provide significant cost savings to a shipper because contract lanes of any type are on average less costly than spot moves. This thesis provides guidelines and suggestions for aggregation when creating bids during the first stage of the truckload procurement process.by Julia M. Collins and R. Ryan Quinlan.M.Eng.in Logistic

An economic evaluation of salt reduction policies to reduce coronary heart disease in England: a policy modeling study

AbstractObjectivesDietary salt intake has been causally linked to high blood pressure and increased risk of cardiovascular events. Cardiovascular disease causes approximately 35% of total UK deaths, at an estimated annual cost of £30 billion. The World Health Organization and the National Institute for Health and Care Excellence have recommended a reduction in the intake of salt in people's diets. This study evaluated the cost-effectiveness of four population health policies to reduce dietary salt intake on an English population to prevent coronary heart disease (CHD).MethodsThe validated IMPACT CHD model was used to quantify and compare four policies: 1) Change4Life health promotion campaign, 2) front-of-pack traffic light labeling to display salt content, 3) Food Standards Agency working with the food industry to reduce salt (voluntary), and 4) mandatory reformulation to reduce salt in processed foods. The effectiveness of these policies in reducing salt intake, and hence blood pressure, was determined by systematic literature review. The model calculated the reduction in mortality associated with each policy, quantified as life-years gained over 10 years. Policy costs were calculated using evidence from published sources. Health care costs for specific CHD patient groups were estimated. Costs were compared against a “do nothing” baseline.ResultsAll policies resulted in a life-year gain over the baseline. Change4life and labeling each gained approximately 1960 life-years, voluntary reformulation 14,560 life-years, and mandatory reformulation 19,320 life-years. Each policy appeared cost saving, with mandatory reformulation offering the largest cost saving, more than £660 million.ConclusionsAll policies to reduce dietary salt intake could gain life-years and reduce health care expenditure on coronary heart disease

Binary Asteroid Encounters with Terrestrial Planets: Timescales and Effects

Many asteroids that make close encounters with terrestrial planets are in a binary configuration. Here we calculate the relevant encounter timescales and investigate the effects of encounters on a binary's mutual orbit. We use a combination of analytical and numerical approaches with a wide range of initial conditions. Our test cases include generic binaries with close, moderate, and wide separations, as well as seven well-characterized near-Earth binaries. We find that close approaches (<10 Earth radii) occur for almost all binaries on 1-10 million year timescales. At such distances, our results suggest substantial modifications to a binary's semi-major axis, eccentricity, and inclination, which we quantify. Encounters within 30 Earth radii typically occur on sub-million year timescales and significantly affect the wider binaries. Important processes in the lives of near-Earth binaries, such as tidal and radiative evolution, can be altered or stopped by planetary encounters.Comment: 8 pages, accepted to A

Dialect Recognition Using a Phone-GMM-Supervector-Based SVM Kernel

In this paper, we introduce a new approach to dialect recognition which relies on the hypothesis that certain phones are realized differently across dialects. Given a speaker’s utterance, we first obtain the most likely phone sequence using a phone recognizer. We then extract GMM Supervectors for each phone instance. Using these vectors, we design a kernel function that computes the similarities of phones between pairs of utterances. We employ this kernel to train SVM classifiers that estimate posterior probabilities, used during recognition. Testing our approach on four Arabic dialects from 30s cuts, we compare our performance to five approaches: PRLM; GMM-UBM; our own improved version of GMM-UBM which employs fMLLR adaptation; our recent discriminative phonotactic approach; and a state-of-the-art system: SDC-based GMM-UBM discriminatively trained. Our kernel-based technique outperforms all these previous approaches; the overall EER of our system is 4.9%

The Art and Patronage of Saint Louis of France

This Exhibition focuses on the iconography Louis IX of France (Saint Louis) established in the Sainte-Chapelle in Paris and how this was reflected in other works he may have commissioned. This is placed in the context of the artistic and stylistic developments of the period. It also examines the role his iconography played in manuscripts in the hundred years after his death. The exhibition closes by showing that the image of Saint Louis, le roi-juste, is still relevant to France today

Democratic Spaces: How Teachers Establish and Sustain Democracy and Education in Their Classrooms

Democratic education focuses on developing students using democratic principles and processes in the classroom. In this study, we aim to understand how self-identified democratic educators practice democratic education in public-school classrooms. Nine participants, teachers in K12 schools, were interviewed for this qualitative study. In investigating how public-school teachers implemented and sustained democratic education in their classrooms, six themes emerged—fostering relationships, empowering students, and teaching and using democratic skills, democratic educative structure, democratic teacher praxis, and obstacles