Orientations of hamiltonian cycles in large digraphs

We prove that, with some exceptions, every digraph with n ≥ 9 vertices and at least (n - 1) (n - 2) + 2 arcs contains all orientations of a Hamiltonian cycle

Unidirectional inline skates

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references.In this thesis, I describe the design, manufacture, assembly, and testing of "1WSkates," a pair of inline skates that prevent backwards motion. The defining element of 1WSkates is the use of a one-way bearing which, along with a fixed axle, prevents certain wheels from rolling backwards. The axle is custom-shaped to lock into an existing inline skate housing. The one-way bearing is attached to the wheel with a custom fitting. The complete 1WSkates allow a user to walk up an incline and roll down the other side, and to use a nordic skiing motion on flat terrain.by Adam J. Goldstein.S.B

Adoption of healthcare information technology and the impact on clinician behavior

Thesis (S.M.)--Harvard-MIT Division of Health Sciences and Technology, 2009."June 2009." Cataloged from PDF version of thesis.Includes bibliographical references (p. 49-52).It is widely believed that healthcare information technology (health IT) can improve care and lower costs. However, the pattern and uptake of beneficial features of health IT is poorly understood, and is an important part of realizing the full benefits of health IT. This thesis examines the factors relating to adoption and use of reporting features within an outpatient practice management system. A retrospective observational study was performed utilizing web log data from a practice management and electronic health record system vendor. Two years of data were analyzed on the use of features within the system in two different scenarios: the use of a newly released custom reporting feature among existing clients, and the use of a physician-level monthly report among new clients. Among these two different populations and features, the first use and subsequent utilization exhibited similar patterns. Using the Bass model of technology diffusion to quantify the adoption of these features, it was found that adoption had a low social component (coefficient of imitation) and a high personal component (coefficient of innovation). One physician's use of a feature in his practice did not appear to influence whether a new physician joining the same practice would use the feature. In addition, the earliest users of a feature tended to utilize that feature more often. Practices and providers that used these features performed better across three of four operational and financial metrics. The purchase and installation of a health IT system by an organization does not ensure that individuals within it will fully utilize the system and realize all the benefits.(cont.) Incentives for health IT should focus on the advantages gained from these systems, and not merely on their purchase. Health IT vendors should be cognizant of the way they introduce new functionality to their clients in order to ensure maximal use.by Adam Weinstein.S.M

Optimization techniques for human computation-enabled data processing systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 119-124).Crowdsourced labor markets make it possible to recruit large numbers of people to complete small tasks that are difficult to automate on computers. These marketplaces are increasingly widely used, with projections of over $1 billion being transferred between crowd employers and crowd workers by the end of 2012. While crowdsourcing enables forms of computation that artificial intelligence has not yet achieved, it also presents crowd workflow designers with a series of challenges including describing tasks, pricing tasks, identifying and rewarding worker quality, dealing with incorrect responses, and integrating human computation into traditional programming frameworks. In this dissertation, we explore the systems-building, operator design, and optimization challenges involved in building a crowd-powered workflow management system. We describe a system called Qurk that utilizes techniques from databases such as declarative workflow definition, high-latency workflow execution, and query optimization to aid crowd-powered workflow developers. We study how crowdsourcing can enhance the capabilities of traditional databases by evaluating how to implement basic database operators such as sorts and joins on datasets that could not have been processed using traditional computation frameworks. Finally, we explore the symbiotic relationship between the crowd and query optimization, enlisting crowd workers to perform selectivity estimation, a key component in optimizing complex crowd-powered workflows.by Adam Marcus.Ph.D

BlendDB : blending table layouts to support efficient browsing of relational databases

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 63-65).The physical implementation of most relational databases follows their logical description, where each relation is stored in its own file or collection of files on disk. Such an implementation is good for queries that filter or aggregate large portions of a single table, and provides reasonable performance for queries that join many records from one table to another. It is much less ideal, however, for join queries that follow paths from a small number of tuples in one table to small collections of tuples in other tables to accumulate facts about a related collection of objects (e.g., co-authors of a particular author in a publications database), since answering such queries involves one or more random I/Os per table involved in the path. If the primary workload of a database consists of many such path queries, as is likely to be the case when supporting browsing-oriented applications, performance will be quite poor. This thesis focuses on optimizing the performance of these kinds of path queries in a system called BlendDB, a relational database that supports on-disk co-location of tuples from different relations. To make BlendDB efficient, the thesis will propose a clustering algorithm that, given knowledge of the database workload, co-locates the tuples of multiple relations if they join along common paths. To support the claim of improved performance, the thesis will include experiments in which BlendDB provides better performance than traditional relational databases on queries against the IMDB movie dataset. Additionally, this thesis will show that BlendDB provides commensurate performance to materialized views while using less disk space, and can achieve better performance than materialized views in exchange for more disk space when users navigate between related items in the database.by Adam Marcus.S.M

Navigation and Exploration in 3D-Game Automated Play Testing

To enable automated software testing, the ability to automatically navigate to a state of interest and to explore all, or at least sufficient number of, instances of such a state is fundamental. When testing a computer game the problem has an extra dimension, namely the virtual world where the game is played on. This world often plays a dominant role in constraining which logical states are reachable, and how to reach them. So, any automated testing algorithm for computer games will inevitably need a layer that deals with navigation on a virtual world. Unlike e.g. navigating through the GUI of a typical web-based application, navigating over a virtual world is much more challenging. This paper discusses how concepts from geometry and graph-based path finding can be applied in the context of game testing to solve the problem of automated navigation and exploration. As a proof of concept, the paper also briefly discusses the implementation of the proposed approach

Conducting retrospective impact analysis to inform a medical research charity’s funding strategies: The case of Asthma UK

© 2013 Hanney et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.BACKGROUND: Debate is intensifying about how to assess the full range of impacts from medical research. Complexity increases when assessing the diverse funding streams of funders such as Asthma UK, a charitable patient organisation supporting medical research to benefit people with asthma. This paper aims to describe the various impacts identified from a range of Asthma UK research, and explore how Asthma UK utilised the characteristics of successful funding approaches to inform future research strategies. METHODS: We adapted the Payback Framework, using it both in a survey and to help structure interviews, documentary analysis, and case studies. We sent surveys to 153 lead researchers of projects, plus 10 past research fellows, and also conducted 14 detailed case studies. These covered nine projects and two fellowships, in addition to the innovative case studies on the professorial chairs (funded since 1988) and the MRC-Asthma UK Centre in Allergic Mechanisms of Asthma (the ‘Centre’) which together facilitated a comprehensive analysis of the whole funding portfolio. We organised each case study to capture whatever academic and wider societal impacts (or payback) might have arisen given the diverse timescales, size of funding involved, and extent to which Asthma UK funding contributed to the impacts. RESULTS: Projects recorded an average of four peer-reviewed journal articles. Together the chairs reported over 500 papers. All streams of funding attracted follow-on funding. Each of the various categories of societal impacts arose from only a minority of individual projects and fellowships. Some of the research portfolio is influencing asthma-related clinical guidelines, and some contributing to product development. The latter includes potentially major breakthroughs in asthma therapies (in immunotherapy, and new inhaled drugs) trialled by university spin-out companies. Such research-informed guidelines and medicines can, in turn, contribute to health improvements. The role of the chairs and the pioneering collaborative Centre is shown as being particularly important. CONCLUSIONS: We systematically demonstrate that all types of Asthma UK’s research funding assessed are making impacts at different levels, but the main societal impacts from projects and fellowships come from a minority of those funded. Asthma UK used the study’s findings, especially in relation to the Centre, to inform research funding strategies to promote the achievement of impact.This study was funded by Asthma UK

Mobility on Demand (MOD) Sandbox Demonstration: Los Angeles County and Puget Sound First and Last Mile Partnership with Via Evaluation Report

This report presents the results of an independent evaluation of the Los Angeles County and Puget Sound First and Last Mile Partnership with Via demonstration, part of the Federal Transit Administration (FTA) Mobility on Demand (MOD) Sandbox program. The demonstration, a joint pilot project in Los Angeles County and the Puget Sound region, executed an on-demand service in partnership with Via providing first- and last-mile access to transit stations within the Los Angeles and Seattle metropolitan regions. Upon launch, customers were able to request subsidized Via rides to or from the participating transit stations within specified zones and times of the day. The Los County Metropolitan Transportation Authority (LA Metro), King County Metro, Sound Transit, and Via (an on-demand transportation network company or TNC) worked together to develop and deploy two analogous pilot projects designed to test the viability of public-private partnerships to deliver access to and from core lines within the public transit networks. Three zones were selected in the Los Angeles region, and five zones were selected in the Puget Sound region. The evaluation of this MOD Sandbox project included 13 hypotheses that explored a number of potential impacts from the project, including mobility, accessibility, public transit ridership, fuel consumption, safety, costs, and lessons learned